A car is travelling along a road. The driver applies the brakes and the car slows down. The brake discs become hot.
Explain why the brake discs become hot as the car slows down.
The engine of the car transfers 4.0 × 107 J of energy from the chemical store of the fuel. Of this energy, 1.2 × 107 J is transferred usefully. Calculate the efficiency of the engine.
The moving parts of the engine are lubricated with oil. Explain how lubricating the moving parts increases the efficiency of the engine.
40 exam-style questions on AQA GCSE Physics 1.2 Conservation and dissipation of energy, covering 1.2.1 Energy transfers in a system and 1.2.2 Efficiency. Each one has a worked solution and a mark scheme showing where the marks go.