The Physics Question Bank

Course: Combined Science + Separate Physics  |  Tier: Foundation + Higher  |  Equation sheet: given in the exam

The equation

energy transferred = power × time    E = P t

Quantity	Symbol	Unit
energy transferred	E	joules (J)
power	P	watts
time	t	seconds (s)

Rearranged: P = E ÷ t  |  t = E ÷ P

Use FIFA for every answer

• F – Formula: write the equation as it appears on the sheet.
• I – Insert: put in the numbers (convert to standard units first).
• F – Fix: rearrange to make the unknown the subject.
• A – Answer: calculate and always give the unit.

Foundation: aim for Q1–8.   Higher: aim for Q4–10. Most questions need rearranging.

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Questions

Q1 (F) A 60 W TV is on for 100 s. Calculate the energy transferred.

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F: E = P t
I: E = 60 × 100
F: E is already the subject
A: 6000 J

Q2 (F) A hairdryer transfers 90 000 J in 60 s. Calculate its power.

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F: E = P t
I: 90 000 = P × 60
F: P = 90 000 ÷ 60
A: 1500 W

Q3 (F) A 2000 W kettle transfers 240 000 J. How long is it on?

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F: E = P t
I: 240 000 = 2000 × t
F: t = 240 000 ÷ 2000
A: 120 s

Q4 (F) A 9 kW electric shower transfers 4.32 MJ. How many minutes is it on?

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Convert first: 9 kW = 9000 W; 4.32 MJ = 4 320 000 J
F: E = P t
I: 4 320 000 = 9000 × t
F: t = 4 320 000 ÷ 9000 = 480 s
A: 8 minutes

Q5 (F) A 400 W games console transfers 1.44 MJ. How many hours is it used for?

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Convert first: 1.44 MJ = 1 440 000 J
F: E = P t
I: 1 440 000 = 400 × t
F: t = 1 440 000 ÷ 400 = 3600 s
A: 1 hour

Q6 (F/H) A TV on standby uses 0.5 W. How much energy does it transfer in 24 hours? Give your answer in kJ.

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Convert first: 24 hours = 24 × 3600 = 86 400 s
F: E = P t
I: E = 0.5 × 86 400
F: E = 43 200 J
A: 43.2 kJ

Q7 (F/H) An electric oven transfers 7.2 MJ in 40 minutes. Calculate its power in kW.

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Convert first: 7.2 MJ = 7 200 000 J; 40 minutes = 2400 s
F: E = P t
I: 7 200 000 = P × 2400
F: P = 7 200 000 ÷ 2400 = 3000 W
A: 3 kW

Q8 (F/H) A 3.0 × 10⁶ W wind turbine runs for one day (8.64 × 10⁴ s). Calculate the energy it generates, to 2 significant figures.

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F: E = P t
I: E = 3.0 × 10⁶ × 8.64 × 10⁴
F: E = 2.592 × 10¹¹ J
A: 2.6 × 10¹¹ J (2 s.f.)

Q9 (H) A heater on the 230 V mains draws 8.0 A for 15 minutes. Calculate the energy transferred in MJ.

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Step 1 – power: P = V I = 230 × 8.0 = 1840 W
Step 2 – energy (15 minutes = 900 s)
F: E = P t
I: E = 1840 × 900
F: E = 1 656 000 J
A: 1.656 MJ (≈ 1.66 MJ)

Q10 (H) A 3.0 kW immersion heater warms 150 kg of water by 40 °C. Assuming no energy is wasted, how many minutes does it take? (c = 4200 J/kg °C)

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Step 1 – energy needed: ΔE = m c Δθ = 150 × 4200 × 40 = 25 200 000 J
Step 2 – time
F: E = P t
I: 25 200 000 = 3000 × t
F: t = 25 200 000 ÷ 3000 = 8400 s
A: 8400 ÷ 60 = 140 minutes