Topic 4 Practice Paper: Energy, work and power — mark scheme
IGCSE · Cambridge IGCSE Physics (Extended (Core + Supplement))
Mark scheme
Energy, work and power
Topic 4 Practice Paper · Maximum mark: 30
Notes for markers
- Award one mark for each point marked [1], up to the marks shown for the part.
- Accept answers worded differently that show the same understanding.
- Units are required where the answer line shows one. ecf: allow an error carried forward.
Section A: Multiple-choice questions[10 marks]
| Question | Answer and marking points | Marks |
|---|---|---|
| Total for Question 1 | 1 | |
| Total for Question 2 | 1 | |
| Total for Question 3 | 1 | |
| Total for Question 4 | 1 | |
| Total for Question 5 | 1 | |
| Total for Question 6 | 1 | |
| Total for Question 7 | 1 | |
| Total for Question 8 | 1 | |
| Total for Question 9 | 1 | |
| Total for Question 10 | 1 |
Section B: Structured questions[20 marks]
| Question | Answer and marking points | Marks |
|---|---|---|
| 11(a) | Ek = ½mv² = ½ × 6.0 × 4.0² = 48 J.
| 2 |
| 11(b) | New Ek = ½ × 6.0 × 3.0² = 27 J; transferred = 48 − 27 = 21 J.
| 2 |
| 11(c) | The internal (thermal) store of the lane, air and ball — friction and drag warm them slightly. [1] | 1 |
| 11(d) | The principle of conservation of energy. [1] | 1 |
| Total for Question 11 | 6 | |
| 12(a) | W = Fd = 220 × 15 = 3300 J.
| 2 |
| 12(b) | Efficiency = (3300 ÷ 6000) × 100% = 55%.
| 2 |
| 12(c) | P = W/t = 3300 ÷ 30 = 110 W.
| 2 |
| Total for Question 12 | 6 | |
| 13(a) | Solar cells: no output at night and reduced output in cloudy weather, whereas diesel is always available and tides are predictable.
| 2 |
| 13(b) | The tidal barrage: tides are driven mainly by the Moon’s gravity. (Diesel is ancient solar energy; solar cells use sunlight directly.)
| 2 |
| 13(c) | It produces no CO₂ or polluting gases at generation (it is renewable and does not burn fuel).
| 1 |
| Total for Question 13 | 5 | |
| 14(a) | ΔEp = mgΔh = 500 × 9.8 × 300 = 1 470 000 J. [1] | 1 |
| 14(b) | Input = useful ÷ 0.40 = 1 470 000 ÷ 0.40 = 3 675 000 J.
| 1 |
| 14(c) | Time = 300 s; P = 3 675 000 ÷ 300 = 12 250 W ≈ 12 kW. [1] | 1 |
| Total for Question 14 | 3 |
— End of mark scheme —