Question 1Warm-upFoundation
A motor transfers 1200 J of energy in 20 s. Calculate its power.
P = E ÷ t.
Worked solution
- W
Answer: W
GCSE & IGCSE physics practice
Power questions and answers
Power is the rate of transferring energy, or doing work: or , in watts (W). 1 watt is 1 joule per second. The questions cover both equations, unit conversions (kW, minutes, hours) and a lifting problem that combines power with GPE.
8 questions · Foundation tier · Every answer is checked as you type it, with a full worked solution. Updated .
Where power comes up
| GCSE (AQA) | Physics and Combined Science, Foundation and Higher. Recall P = E ÷ t and P = W ÷ t (on AQA's list of equations to learn). |
|---|---|
| Cambridge IGCSE (0625) | Core: define power as work done per unit time and energy transferred per unit time; recall and use P = W ÷ t and P = ΔE ÷ t. |
The method
- P = E ÷ t, with energy in J and time in s.
- Rearranged: E = P × t and t = E ÷ P.
- 1 kW = 1000 W; time must be in seconds (minutes × 60).
- For lifting: work done = weight × height, then divide by time.
Power questions
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Warm-up
Question 2Warm-upFoundation
A kettle has a power of 2000 W. How much energy does it transfer in 90 s?
E = P × t.
Worked solution
- J
Answer: J
Exam-style
Question 3Exam-styleFoundation
A 1.5 kW heater is switched on for 4 minutes. How much energy does it transfer?
Convert to W and seconds first.
Worked solution
- W and min s
- J
Answer: J
Question 4Exam-styleFoundation
A lamp transfers 7200 J at a power of 40 W. How long was it on?
t = E ÷ P.
Worked solution
- s
Answer: s (3 minutes)
Question 5Exam-styleFoundation
A weightlifter does 2400 J of work in 1.2 s. Calculate their power output.
P = W ÷ t.
Worked solution
- W
Answer: W
Question 6Exam-styleFoundation
Motor A transfers 3000 J in 15 s. Motor B transfers 5000 J in 20 s. Which is more powerful, and what is its power?
Work out both powers.
Worked solution
- A: W
- B: W, so B is more powerful
Answer: Motor B, W (A is W)
Challenge
Question 7ChallengeFoundation
A motor lifts a 50 kg load through 6 m in 4 s. Calculate its useful power output. ( N/kg)
Work done = mgh, then divide by time.
Worked solution
- Work done J
- W
Answer: W
Question 8ChallengeFoundation
A 60 kg student runs up stairs 3 m high in 2.5 s. Calculate their power. ( N/kg)
Energy gained = GPE.
Worked solution
- GPE J
- W
Answer: W (about 710 W)
Common mistakes
- Leaving time in minutes or hours.
- Mixing up kW and W.
- Multiplying instead of dividing.
Stuck on one of these?
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Sources
The questions are our own. The “where it comes up” notes are from each board's published specification, checked on 27 October 2026:
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