Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: T = 0.02 s. Frequency f?
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.02 s. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Frequency f. Circle that word — that is the missing variable.
Find
We are required to find: Frequency f. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write f = 50 Hz with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Frequency f.
In other words — as if you have never seen this before
f = 1T. Frequency is how many cycles in one second.
2. What do we already know?
Period T = 0.02 s. Unknown: f.
3. Which method — and why this one?
f = 1T. Frequency is how many cycles in one second.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 0.02 s. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Frequency f. Circle that word — that is the missing variable.
Find: We are required to find: Frequency f. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write f = 50 Hz with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Frequency f.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Period T = 0.02 s. Unknown: f.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
f = 1T. Frequency is how many cycles in one second.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Write f = 1/T
f=10.02=50 Hz.
f=50 Hz
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
50 Hz
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
50 Hz
Copy onto your answer sheet — in this order
Formula: f=50 Hz
Answer: 50 Hz
6. Check it like a marker
50 cycles × 0.02 s = 1 s. Consistent.
7. A trap first-timers fall into
Leaving f = 0.02 treats period as frequency.
1.2 · 10 Marks · Electric circuits: Ohm’s law and power
A 2.0 kW heater runs for 3.0 h. Electricity costs R3.00 per kWh. Cost?
Electric circuits: Ohm’s law and power
Formulas
V=IR
Ohm’s law (constant temperature)
Rs=R₁+R₂+…1Rp=1R₁+1R₂+…
Series and parallel resistors
P=VI=I²R=V²RW=Pt
Electrical power and energy (1 kWh = 3.6 × 10⁶ J)
Notes: P=2.0 kW, t=3.0 h, tariff R3.00 per kWh.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A 2.0 kW heater runs for 3.0 h. Electricity costs R3.00 per kWh. Cost?
Before any working — hunt first
Given
Numbers and units already in the sentence: 2.0 kW · 3.0 h · R3.00 per. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Cost. Circle that word — that is the missing variable.
Find
We are required to find: Cost. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write W = 6.0 kWh with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Cost.
In other words — as if you have never seen this before
Energy in kWh = power in kW × time in hours. Cost = kWh × tariff.
2. What do we already know?
P=2.0 kW, t=3.0 h, tariff R3.00 per kWh.
3. Which method — and why this one?
Energy in kWh = power in kW × time in hours. Cost = kWh × tariff.
4. Step-by-step working
01 / 05
Energy
W=Pt=2.0 kW×3.0 h=6.0 kWh.
W=6.0 kWh
Why this step: One job per line so you can find a slip, and so a marker can follow the marks.
02 / 05
Cost
Cost=6.0×R3.00=R18.00.
R18.00
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
03 / 05
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
04 / 05
Step F — Box the answer with its unit
R18.00
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
05 / 05
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
R18.00
Copy onto your answer sheet — in this order
Formula: W=6.0 kWh
Answer: R18.00
6. Check it like a marker
6.0 kWh=6.0×3.6×10⁶ J=2.16×10⁷ J. R18.00R3.00=6 kWh. Consistent.
7. A trap first-timers fall into
R6.00 stops at the energy; R18 000 uses 2 000 W instead of 2.0 kW.
2.1 · 10 Marks
A 3 Ω and 6 Ω in parallel. R_eq?
Notes: Two resistors in parallel: 3 Ω and 6 Ω.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A 3 Ω and 6 Ω in parallel. R_eq?
Before any working — hunt first
Given
Numbers and units already in the sentence: 3 Ω · 6 Ω. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: R_eq. Circle that word — that is the missing variable.
Find
We are required to find: R_eq. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write 1R=12 with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives R_eq.
In other words — as if you have never seen this before
1R=1R1 + 1R2. Parallel equivalent is smaller than the smallest branch.
2. What do we already know?
Two resistors in parallel: 3 Ω and 6 Ω.
3. Which method — and why this one?
1R=1R1 + 1R2. Parallel equivalent is smaller than the smallest branch.
4. Step-by-step working
01 / 05
Reciprocals
1R=13+16=12.
1R=12
Why this step: One job per line so you can find a slip, and so a marker can follow the marks.
02 / 05
Invert
R=2 Ω.
R=2 Ω
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
03 / 05
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
04 / 05
Step F — Box the answer with its unit
2 Ω
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
05 / 05
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
2 Ω
Copy onto your answer sheet — in this order
Formula: 1R=12
Answer: 2 Ω
6. Check it like a marker
2 Ω is less than 3 Ω. Parallel must be.
7. A trap first-timers fall into
Adding 3+6 = 9 is series. The word “parallel” is in the question.
2.2 · 12 Marks
Doppler: source towards you. Observed f is
Notes: Source moving towards a stationary listener.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Doppler: source towards you. Observed f is
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Observed f is. Circle that word — that is the missing variable.
Find
We are required to find: Observed f is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write f' > f with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Observed f is.
In other words — as if you have never seen this before
Crests bunch up ahead of a moving source. Pitch rises.
2. What do we already know?
Source moving towards a stationary listener.
3. Which method — and why this one?
Crests bunch up ahead of a moving source. Pitch rises.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Observed f is. Circle that word — that is the missing variable.
Find: We are required to find: Observed f is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write f' > f with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Observed f is.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Source moving towards a stationary listener.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Crests bunch up ahead of a moving source. Pitch rises.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Picture crests
Wavelength in front shrinks, so f = v/λ rises.
f' > f
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
higher
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
higher
Copy onto your answer sheet — in this order
Formula: f' > f
Answer: higher
6. Check it like a marker
Ambulance siren rises as it comes toward you.
7. A trap first-timers fall into
Do not swap source and listener formulas on the data sheet.
5 · 3 Marks · Electrostatics: charge & Coulomb
Two charges +q and +q. If r doubles, F becomes
Electrostatics: charge & Coulomb
Formulas
Q=n e
Quantisation of charge
F=k Q₁ Q₂r²
Coulomb’s law
Notes: Coulomb: F ∝ 1r². r → 2r. Charges stay the same.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Two charges +q and +q. If r doubles, F becomes
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: If r doubles, F becomes. Circle that word — that is the missing variable.
Find
We are required to find: If r doubles, F becomes. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write r² → 4r² with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives If r doubles, F becomes.
In other words — as if you have never seen this before
Inverse square: double the distance, force drops to 14.
2. What do we already know?
Coulomb: F ∝ 1r². r → 2r. Charges stay the same.
3. Which method — and why this one?
Inverse square: double the distance, force drops to 14.
4. Step-by-step working
01 / 05
Scale r
r → 2r so r² → 4 r².
r²→4r²
Why this step: One job per line so you can find a slip, and so a marker can follow the marks.
02 / 05
Scale F
Fnew=F4.
F ∝ 1r²
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
03 / 05
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
04 / 05
Step F — Box the answer with its unit
a quarter
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
05 / 05
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
a quarter
Copy onto your answer sheet — in this order
Formula: r² → 4r²
Answer: a quarter
6. Check it like a marker
Same pattern as gravity. Markers want the words “inverse square”.
7. A trap first-timers fall into
Half would be inverse, not inverse square. Read the power on r.
6 · 3 Marks · Friction
Static friction can be
Friction
Formulas
fs ≤ μs N
Static friction (maximum at the point of slipping)
fk=μk N
Kinetic friction
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Static friction can be
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Static friction can be. Circle that word — that is the missing variable.
Find
We are required to find: Static friction can be. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Only the maximum is μ_s N. Then substitute the given, one line at a time, to get Static friction can be.
In other words — as if you have never seen this before
Only the maximum is μ_s N.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Only the maximum is μ_s N.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Static friction can be. Circle that word — that is the missing variable.
Find: We are required to find: Static friction can be. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: Only the maximum is μ_s N. Then substitute the given, one line at a time, to get Static friction can be.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Only the maximum is μ_s N.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Only the maximum is μ_s N.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
any value from 0 up to μ_s N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
any value from 0 up to μ_s N
Copy onto your answer sheet — in this order
Answer: any value from 0 up to μ_s N
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
7 · 2 Marks · Longitudinal waves & sound
Sound needs
Longitudinal waves & sound
Formulas
v=f λ
Sound is a wave
Notes: Sound needs
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Sound needs
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Sound needs. Circle that word — that is the missing variable.
Find
We are required to find: Sound needs. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Sound is a mechanical wave. Then substitute the given, one line at a time, to get Sound needs.
In other words — as if you have never seen this before
Sound is a mechanical wave. It cannot travel in a vacuum.
2. What do we already know?
Sound needs
3. Which method — and why this one?
Sound is a mechanical wave. It cannot travel in a vacuum.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Sound needs. Circle that word — that is the missing variable.
Find: We are required to find: Sound needs. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: Sound is a mechanical wave. Then substitute the given, one line at a time, to get Sound needs.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Sound needs
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Sound is a mechanical wave. It cannot travel in a vacuum.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Sound is a mechanical wave. It cannot travel in a vacuum.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
a medium
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
a medium
Copy onto your answer sheet — in this order
Answer: a medium
6. Check it like a marker
Sound is a mechanical wave. It cannot travel in a vacuum.
7. A trap first-timers fall into
a vacuum
8 · 2 Marks · Friction
Kinetic friction f_k =
Friction
Formulas
fs ≤ μs N
Static friction (maximum at the point of slipping)
fk=μk N
Kinetic friction
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Kinetic friction f_k =
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Kinetic friction f_k =. Circle that word — that is the missing variable.
Find
We are required to find: Kinetic friction f_k =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Opposes sliding, magnitude μ_k N. Then substitute the given, one line at a time, to get Kinetic friction f_k =.
In other words — as if you have never seen this before
Opposes sliding, magnitude μ_k N.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Opposes sliding, magnitude μ_k N.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Kinetic friction f_k =. Circle that word — that is the missing variable.
Find: We are required to find: Kinetic friction f_k =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: Opposes sliding, magnitude μ_k N. Then substitute the given, one line at a time, to get Kinetic friction f_k =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Opposes sliding, magnitude μ_k N.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Opposes sliding, magnitude μ_k N.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
μ_k N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
μ_k N
Copy onto your answer sheet — in this order
Answer: μ_k N
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
9 · 3 Marks · Friction
A 2 kg object pulled with 10 N, friction 4 N. a =
Friction
Formulas
fs ≤ μs N
Static friction (maximum at the point of slipping)
fk=μk N
Kinetic friction
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A 2 kg object pulled with 10 N, friction 4 N. a =
Before any working — hunt first
Given
Numbers and units already in the sentence: 2 kg · 10 N · 4 N. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: a =. Circle that word — that is the missing variable.
Find
We are required to find: a =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: F_net=6 N, a=62=3. Then substitute the given, one line at a time, to get a =.
In other words — as if you have never seen this before
Fnet=6 N, a=62=3.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 2 kg · 10 N · 4 N. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Fnet=6 N, a=62=3.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 2 kg · 10 N · 4 N. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: a =. Circle that word — that is the missing variable.
Find: We are required to find: a =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: F_net=6 N, a=62=3. Then substitute the given, one line at a time, to get a =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 2 kg · 10 N · 4 N. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Fnet=6 N, a=62=3.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Fnet=6 N, a=62=3.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
3 m·s⁻²
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
3 m·s⁻²
Copy onto your answer sheet — in this order
Answer: 3 m·s⁻²
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
10 · 4 Marks · Electric fields
Field lines of an isolated positive charge
Electric fields
Formulas
E=Fq
Field definition
E=Vd
Uniform field between plates
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Field lines of an isolated positive charge
In other words — as if you have never seen this before
Start on + end on −.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Start on + end on −.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Start on + end on −.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Start on + end on −.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
radiate outward
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
radiate outward
Copy onto your answer sheet — in this order
Answer: radiate outward
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
11 · 2 Marks · Newton’s laws
A 50 kg kibble, Fnet=150 N down a mine shaft. a=
Newton’s laws
Formulas
Fnet=m a
Newton 2
Notes: m = 50 kg. F_net = 150 N. Unknown: acceleration a. The word net means “already the leftover force”.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A 50 kg kibble, F_net = 150 N down a mine shaft. a =
Before any working — hunt first
Given
Numbers and units already in the sentence: 50 kg · 150 N. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: a =. Circle that word — that is the missing variable.
Find
We are required to find: a =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write a = Fnetm with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives a =.
In other words — as if you have never seen this before
Newton 2 in words: leftover force equals mass times acceleration. So a = Fnetm.
2. What do we already know?
m = 50 kg. F_net = 150 N. Unknown: acceleration a. The word net means “already the leftover force”.
3. Which method — and why this one?
Newton 2 in words: leftover force equals mass times acceleration. So a = Fnetm.
4. Step-by-step working
01 / 06
Write Newton 2
F_net = m a, therefore a = Fnetm. Do not add g — net force already includes whatever gravity leftover there is.
a=Fnetm
Why this step: If the paper had given weight and tension separately you would subtract first. Here they already gave F_net.
02 / 06
Substitute
a = 15050. Units: N is kg·m·s⁻², so Nkg=m·s⁻². The unit we want falls out.
a=15050
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 06
Calculate
15050=3. So a = 3 m·s⁻² downward, same direction as F_net.
a=3 m·s⁻²
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
04 / 06
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
05 / 06
Step F — Box the answer with its unit
3 m·s⁻²
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
06 / 06
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
3 m·s⁻²
Copy onto your answer sheet — in this order
Formula: a=Fnetm
Answer: 3 m·s⁻²
6. Check it like a marker
3 × 50 = 150 N. Rebuilds the given force. 9.8 m·s⁻² would be free fall with no other forces.
7. A trap first-timers fall into
m × F = 7500. That multiplies mass by force, which is not a Newton law. Force over mass, never mass times force.
12 · 2 Marks
A 20 kg bag of maize, F_net = 40 N. a =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A 20 kg bag of maize, F_net = 40 N. a =
Before any working — hunt first
Given
Numbers and units already in the sentence: 20 kg · 40 N. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: a =. Circle that word — that is the missing variable.
Find
We are required to find: a =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 2 m·s⁻². Then substitute the given, one line at a time, to get a =.
In other words — as if you have never seen this before
2 m·s⁻²
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 20 kg · 40 N. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
2 m·s⁻²
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 20 kg · 40 N. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: a =. Circle that word — that is the missing variable.
Find: We are required to find: a =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: 2 m·s⁻². Then substitute the given, one line at a time, to get a =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 20 kg · 40 N. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
2 m·s⁻²
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Newton 2: a=Fnetm=4020=2 m·s⁻². Force over mass, never mass over force.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
2 m·s⁻²
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
2 m·s⁻²
Copy onto your answer sheet — in this order
Answer: 2 m·s⁻²
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
13 · 2 Marks
m = 8 kg and a = 3 m·s⁻². F_net =
Notes: m = 8 kg and a = 3 m·s⁻². F_net =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: m = 8 kg and a = 3 m·s⁻². F_net =
Before any working — hunt first
Given
Numbers and units already in the sentence: 8 kg · 3 m·s⁻². Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: F_net =. Circle that word — that is the missing variable.
Find
We are required to find: F_net =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: F_net = ma = 24 N. Then substitute the given, one line at a time, to get F_net =.
In other words — as if you have never seen this before
Fnet=ma=24 N.
2. What do we already know?
m = 8 kg and a = 3 m·s⁻². F_net =
3. Which method — and why this one?
Fnet=ma=24 N.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 8 kg · 3 m·s⁻². Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: F_net =. Circle that word — that is the missing variable.
Find: We are required to find: F_net =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: F_net = ma = 24 N. Then substitute the given, one line at a time, to get F_net =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
m = 8 kg and a = 3 m·s⁻². F_net =
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Fnet=ma=24 N.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Fnet=ma=24 N.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
24 N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
24 N
Copy onto your answer sheet — in this order
Answer: 24 N
6. Check it like a marker
Fnet=ma=24 N.
7. A trap first-timers fall into
11 N
14 · 2 Marks · Refraction & TIR
n = cv. If n=1.33, light in the medium is
Refraction & TIR
Formulas
n₁ sinθ₁=n₂ sinθ₂
Snell’s law
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: n = cv. If n=1.33, light in the medium is
Before any working — hunt first
Given
Numbers and units already in the sentence: 1.33. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: 33, light in the medium is. Circle that word — that is the missing variable.
Find
We are required to find: 33, light in the medium is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: v=cn. Then substitute the given, one line at a time, to get 33, light in the medium is.
In other words — as if you have never seen this before
v=cn.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 1.33. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
v=cn.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 1.33. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: 33, light in the medium is. Circle that word — that is the missing variable.
Find: We are required to find: 33, light in the medium is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: v=cn. Then substitute the given, one line at a time, to get 33, light in the medium is.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 1.33. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
v=cn.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
v=cn.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
slower than in vacuum
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
slower than in vacuum
Copy onto your answer sheet — in this order
Answer: slower than in vacuum
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
15 · 2 Marks
ε=12 V, r=1 Ω, R=5 Ω. Current=
Notes: ε=12 V, r=1 Ω, R=5 Ω. Current=
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: ε = 12 V, r = 1 Ω, R = 5 Ω. Current =
Before any working — hunt first
Given
Numbers and units already in the sentence: 12 V · 1 Ω · 5 Ω. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Current =. Circle that word — that is the missing variable.
Find
We are required to find: Current =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: I = ε / (R + r) = 126=2 A. Then substitute the given, one line at a time, to get Current =.
In other words — as if you have never seen this before
I=ε(R + r)=126=2 A.
2. What do we already know?
ε=12 V, r=1 Ω, R=5 Ω. Current=
3. Which method — and why this one?
I=ε(R + r)=126=2 A.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 12 V · 1 Ω · 5 Ω. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Current =. Circle that word — that is the missing variable.
Find: We are required to find: Current =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: I = ε / (R + r) = 126=2 A. Then substitute the given, one line at a time, to get Current =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
ε=12 V, r=1 Ω, R=5 Ω. Current=
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
I=ε(R + r)=126=2 A.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
I=ε(R + r)=126=2 A.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
2 A
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
2 A
Copy onto your answer sheet — in this order
Answer: 2 A
6. Check it like a marker
I=ε(R + r)=126=2 A.
7. A trap first-timers fall into
12 A
16 · 2 Marks
m=5 kg, a=2 ms². Fnet?
Notes: m=5 kg. a=2 m·s⁻².
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: m = 5 kg, a = 2 ms². F_net?
Before any working — hunt first
Given
Numbers and units already in the sentence: 5 kg · 2 ms². Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: F_net. Circle that word — that is the missing variable.
Find
We are required to find: F_net. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write F = 10 N with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives F_net.
In other words — as if you have never seen this before
Fnet=ma.
2. What do we already know?
m=5 kg. a=2 m·s⁻².
3. Which method — and why this one?
Fnet=ma.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 5 kg · 2 ms². Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: F_net. Circle that word — that is the missing variable.
Find: We are required to find: F_net. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write F = 10 N with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives F_net.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
m=5 kg. a=2 m·s⁻².
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Fnet=ma.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Newton 2
F=5×2=10 N.
F=10 N
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
10 N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
10 N
Copy onto your answer sheet — in this order
Formula: F=10 N
Answer: 10 N
6. Check it like a marker
a=105=2. Recovers a.
7. A trap first-timers fall into
Do not add m + a.
17 · 2 Marks
p before = 12 kg·ms. Isolated. p after?
Notes: Isolated system. No external impulse.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: p before = 12 kg·ms. Isolated. p after?
Before any working — hunt first
Given
Numbers and units already in the sentence: 12 kg·ms. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: p after. Circle that word — that is the missing variable.
Find
We are required to find: p after. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write p = 12 with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives p after.
In other words — as if you have never seen this before
Conservation of momentum: p_after = p_before.
2. What do we already know?
Isolated system. No external impulse.
3. Which method — and why this one?
Conservation of momentum: p_after = p_before.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 12 kg·ms. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: p after. Circle that word — that is the missing variable.
Find: We are required to find: p after. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write p = 12 with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives p after.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Isolated system. No external impulse.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Conservation of momentum: p_after = p_before.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Conserve p
Total p stays 12 kg·ms.
p=12
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
12 kg·ms
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
12 kg·ms
Copy onto your answer sheet — in this order
Formula: p=12
Answer: 12 kg·ms
6. Check it like a marker
If it changed, some external force acted. The paper said isolated.
7. A trap first-timers fall into
Halving p is energy thinking. Momentum and kinetic energy are different.
18 · 4 Marks · Longitudinal waves & sound
Particles in a sound wave vibrate
Longitudinal waves & sound
Formulas
v=f λ
Sound is a wave
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Particles in a sound wave vibrate
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Particles in a sound wave vibrate. Circle that word — that is the missing variable.
Find
We are required to find: Particles in a sound wave vibrate. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Longitudinal. Then substitute the given, one line at a time, to get Particles in a sound wave vibrate.
In other words — as if you have never seen this before
Longitudinal.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Longitudinal.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Particles in a sound wave vibrate. Circle that word — that is the missing variable.
Find: We are required to find: Particles in a sound wave vibrate. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: Longitudinal. Then substitute the given, one line at a time, to get Particles in a sound wave vibrate.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Longitudinal.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Longitudinal.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
parallel to the direction of travel
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
parallel to the direction of travel
Copy onto your answer sheet — in this order
Answer: parallel to the direction of travel
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
19 · 4 Marks · Refraction & TIR
Critical angle exists only when light goes
Refraction & TIR
Formulas
n₁ sinθ₁=n₂ sinθ₂
Snell’s law
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Critical angle exists only when light goes
In other words — as if you have never seen this before
Need n1>n2.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Need n1>n2.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
Need n1>n2.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
Need n1>n2.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
denser to rarer
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
denser to rarer
Copy onto your answer sheet — in this order
Answer: denser to rarer
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
20 · 3 Marks
ε=6 V, r=0.5 Ω, R=2.5 Ω. I=
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: ε=6 V, r=0.5 Ω, R=2.5 Ω. I=
Before any working — hunt first
Given
Numbers and units already in the sentence: 6 V · 0.5 Ω · 2.5 Ω. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: I=. Circle that word — that is the missing variable.
Find
We are required to find: I=. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 2 A. Then substitute the given, one line at a time, to get I=.
In other words — as if you have never seen this before
2 A
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 6 V · 0.5 Ω · 2.5 Ω. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
2 A
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 6 V · 0.5 Ω · 2.5 Ω. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: I=. Circle that word — that is the missing variable.
Find: We are required to find: I=. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: 2 A. Then substitute the given, one line at a time, to get I=.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 6 V · 0.5 Ω · 2.5 Ω. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
2 A
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Reason
I=63=2.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
2 A
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
2 A
Copy onto your answer sheet — in this order
Answer: 2 A
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
21 · 2 Marks · Newton’s laws
Newton I says a body stays at rest or uniform velocity unless
Newton’s laws
Formulas
Fnet=m a
Newton 2
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Newton I says a body stays at rest or uniform velocity unless
In other words — as if you have never seen this before
InertiaN1.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
InertiaN1.
4. Step-by-step working
01 / 07
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 07
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
03 / 07
Step C — Name the method in words
InertiaN1.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
04 / 07
Working
InertiaN1.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
05 / 07
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
06 / 07
Step F — Box the answer with its unit
a net force acts
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
07 / 07
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
a net force acts
Copy onto your answer sheet — in this order
Answer: a net force acts
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Efficiency = usefulinput. Useful 80 J, input 100 J
Before any working — hunt first
Given
Numbers and units already in the sentence: 80 J · 100 J. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Useful 80 J, input 100 J. Circle that word — that is the missing variable.
Find
We are required to find: Useful 80 J, input 100 J. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write 80% with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Useful 80 J, input 100 J.
In other words — as if you have never seen this before
Efficiency = (useful / input) × 100%.
2. What do we already know?
Useful energy 80 J. Input 100 J.
3. Which method — and why this one?
Efficiency = (useful / input) × 100%.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 80 J · 100 J. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Useful 80 J, input 100 J. Circle that word — that is the missing variable.
Find: We are required to find: Useful 80 J, input 100 J. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write 80% with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Useful 80 J, input 100 J.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Useful energy 80 J. Input 100 J.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Efficiency = (useful / input) × 100%.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Divide then percent
80100=0.8=80%.
80%
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
80%
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
80%
Copy onto your answer sheet — in this order
Formula: 80%
Answer: 80%
6. Check it like a marker
20 J was wasted. 80+20=100.
7. A trap first-timers fall into
Writing 80 without % loses the unit the memo wants.
23 · 2 Marks · Longitudinal waves & sound
Sound is a
Longitudinal waves & sound
Formulas
v=f λ
Sound is a wave
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Sound is a
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Sound is a. Circle that word — that is the missing variable.
Find
We are required to find: Sound is a. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Particles vibrate parallel to the direction of travel. Then substitute the given, one line at a time, to get Sound is a.
In other words — as if you have never seen this before
Particles vibrate parallel to the direction of travel.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Particles vibrate parallel to the direction of travel.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Sound is a. Circle that word — that is the missing variable.
Find: We are required to find: Sound is a. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: Particles vibrate parallel to the direction of travel. Then substitute the given, one line at a time, to get Sound is a.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Particles vibrate parallel to the direction of travel.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Particles vibrate parallel to the direction of travel.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
longitudinal wave
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
longitudinal wave
Copy onto your answer sheet — in this order
Answer: longitudinal wave
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
24 · 2 Marks
A 6 N force does work through 3 m in the direction of F. W?
Notes: F = 6 N. Δx = 3 m. Force parallel to displacement.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A 6 N force does work through 3 m in the direction of F. W?
Before any working — hunt first
Given
Numbers and units already in the sentence: 6 N · 3 m. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: W. Circle that word — that is the missing variable.
Find
We are required to find: W. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write W = 18 J with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives W.
In other words — as if you have never seen this before
W=F Δx cosθ. θ=0 so cos=1.
2. What do we already know?
F = 6 N. Δx = 3 m. Force parallel to displacement.
3. Which method — and why this one?
W=F Δx cosθ. θ=0 so cos=1.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 6 N · 3 m. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: W. Circle that word — that is the missing variable.
Find: We are required to find: W. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write W = 18 J with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives W.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
F = 6 N. Δx = 3 m. Force parallel to displacement.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
W=F Δx cosθ. θ=0 so cos=1.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
W = FΔx
W=6×3=18 J.
W=18 J
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
18 J
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
18 J
Copy onto your answer sheet — in this order
Formula: W=18 J
Answer: 18 J
6. Check it like a marker
Joule is N·m. 6 N through 3 m is 18 J.
7. A trap first-timers fall into
If the force were perpendicular, work would be 0. Here it is parallel.
25 · 2 Marks
m=10 kg, a=2 m·s⁻². Fnet=
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: m=10 kg, a=2 m·s⁻². F_net =
Before any working — hunt first
Given
Numbers and units already in the sentence: 10 kg · 2 m·s⁻². Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: F_net =. Circle that word — that is the missing variable.
Find
We are required to find: F_net =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 20 N. Then substitute the given, one line at a time, to get F_net =.
In other words — as if you have never seen this before
20 N
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 10 kg · 2 m·s⁻². Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
20 N
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 10 kg · 2 m·s⁻². Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: F_net =. Circle that word — that is the missing variable.
Find: We are required to find: F_net =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: 20 N. Then substitute the given, one line at a time, to get F_net =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 10 kg · 2 m·s⁻². Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
20 N
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Reason
F=ma=20 N.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
20 N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
20 N
Copy onto your answer sheet — in this order
Answer: 20 N
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
26 · 2 Marks
Two 8 Ω resistors in series. R_eq =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Two 8 Ω resistors in series. R_eq =
Before any working — hunt first
Given
Numbers and units already in the sentence: 8 Ω. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: R_eq =. Circle that word — that is the missing variable.
Find
We are required to find: R_eq =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 16 Ω. Then substitute the given, one line at a time, to get R_eq =.
In other words — as if you have never seen this before
16 Ω
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 8 Ω. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
16 Ω
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 8 Ω. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: R_eq =. Circle that word — that is the missing variable.
Find: We are required to find: R_eq =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: 16 Ω. Then substitute the given, one line at a time, to get R_eq =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 8 Ω. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
16 Ω
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
Series resistors add: 8 + 8 = 16 Ω. Current has only one path, so resistances pile up.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
16 Ω
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
16 Ω
Copy onto your answer sheet — in this order
Answer: 16 Ω
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
27 · 3 Marks
F=IℓB at 90°, I=5 A, ℓ=0.2 m, B=0.4 T
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: F = IℓB at 90°, I = 5 A, ℓ = 0.2 m, B = 0.4 T
Before any working — hunt first
Given
Numbers and units already in the sentence: 90° · 5 A · 0.2 m · 0.4 T. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: 4 T. Circle that word — that is the missing variable.
Find
We are required to find: 4 T. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 0. Then substitute the given, one line at a time, to get 4 T.
In other words — as if you have never seen this before
0.4 N
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 90° · 5 A · 0.2 m · 0.4 T. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
0.4 N
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 90° · 5 A · 0.2 m · 0.4 T. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: 4 T. Circle that word — that is the missing variable.
Find: We are required to find: 4 T. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: 0. Then substitute the given, one line at a time, to get 4 T.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 90° · 5 A · 0.2 m · 0.4 T. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
0.4 N
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
5 × 0.2 × 0.4 × sin 90° = 0.4 N. sin 90° = 1, so just multiply the three numbers.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
0.4 N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.4 N
Copy onto your answer sheet — in this order
Answer: 0.4 N
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
28 · 4 Marks · Friction
N = 100 N, μ_s = 0.4. Max static friction is
Friction
Formulas
fs ≤ μs N
Static friction (maximum at the point of slipping)
fk=μk N
Kinetic friction
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: N = 100 N, μ_s = 0.4. Max static friction is
Before any working — hunt first
Given
Numbers and units already in the sentence: 100 N · 0.4. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Max static friction is. Circle that word — that is the missing variable.
Find
We are required to find: Max static friction is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: f_s(max) = μ_s N = 40 N. Then substitute the given, one line at a time, to get Max static friction is.
In other words — as if you have never seen this before
fs(max)=μs N=40 N.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 100 N · 0.4. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
fs(max)=μs N=40 N.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 100 N · 0.4. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Max static friction is. Circle that word — that is the missing variable.
Find: We are required to find: Max static friction is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: f_s(max) = μ_s N = 40 N. Then substitute the given, one line at a time, to get Max static friction is.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
Copy these onto the left of your page, one per line, with units: 100 N · 0.4. Mixing cm with m, or minutes with seconds, loses a method mark.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
fs(max)=μs N=40 N.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
fs(max)=μs N=40 N.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
40 N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
40 N
Copy onto your answer sheet — in this order
Answer: 40 N
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
29 · 3 Marks
g on Earth 9.8, on Moon ≈ 1.6. Mass of 10 kg on Moon?
Notes: m = 10 kg on Earth. Moved to the Moon.
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: g on Earth 9.8, on Moon ≈ 1.6. Mass of 10 kg on Moon?
Before any working — hunt first
Given
Numbers and units already in the sentence: 9.8 · 1.6 · 10 kg. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Mass of 10 kg on Moon. Circle that word — that is the missing variable.
Find
We are required to find: Mass of 10 kg on Moon. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write m = 10 kg with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Mass of 10 kg on Moon.
In other words — as if you have never seen this before
Mass is the amount of matter. It does not change. Weight does.
2. What do we already know?
m = 10 kg on Earth. Moved to the Moon.
3. Which method — and why this one?
Mass is the amount of matter. It does not change. Weight does.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 9.8 · 1.6 · 10 kg. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Mass of 10 kg on Moon. Circle that word — that is the missing variable.
Find: We are required to find: Mass of 10 kg on Moon. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: Write m = 10 kg with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Mass of 10 kg on Moon.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
m = 10 kg on Earth. Moved to the Moon.
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
Mass is the amount of matter. It does not change. Weight does.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Mass is invariant
mmoon=10 kg. Weight would be 16 N.
m=10 kg
Why this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
10 kg
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
10 kg
Copy onto your answer sheet — in this order
Formula: m=10 kg
Answer: 10 kg
6. Check it like a marker
W_moon = 10 × 1.6 = 16 N. That is weight, not mass.
7. A trap first-timers fall into
1.6 kg confuses g with mass. 16 N is weight. The asking-word is mass.
30 · 2 Marks
F=IℓB at 90°. I=3 A, ℓ=0.5 m, B=0.4 T. F=
Notes: F=IℓB at 90°. I=3 A, ℓ=0.5 m, B=0.4 T. F=
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: F = IℓB at 90°. I = 3 A, ℓ = 0.5 m, B = 0.4 T. F =
Before any working — hunt first
Given
Numbers and units already in the sentence: 90° · 3 A · 0.5 m · 0.4 T. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: F =. Circle that word — that is the missing variable.
Find
We are required to find: F =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: F = 3 × 0. Then substitute the given, one line at a time, to get F =.
In other words — as if you have never seen this before
F=3×0.5×0.4=0.6 N.
2. What do we already know?
F=IℓB at 90°. I=3 A, ℓ=0.5 m, B=0.4 T. F=
3. Which method — and why this one?
F=3×0.5×0.4=0.6 N.
4. Step-by-step working
01 / 08
Step A — Read the question twice
Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
02 / 08
Step A2 — Hunt: Given, Missing, Find, Calculate
Given: Numbers and units already in the sentence: 90° · 3 A · 0.5 m · 0.4 T. Copy each one into a column. A name without a number is not given.
Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: F =. Circle that word — that is the missing variable.
Find: We are required to find: F =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate: What we need to calculate: F = 3 × 0. Then substitute the given, one line at a time, to get F =.
Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
03 / 08
Step B — Write the given in a column
F=IℓB at 90°. I=3 A, ℓ=0.5 m, B=0.4 T. F=
Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
04 / 08
Step C — Name the method in words
F=3×0.5×0.4=0.6 N.
Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
05 / 08
Working
F=3×0.5×0.4=0.6 N.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
06 / 08
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
07 / 08
Step F — Box the answer with its unit
0.6 N
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
08 / 08
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.