A petrol engine is supplied with 600 kJ of energy.
150 kJ is transferred to the kinetic store of the car.
390 kJ is transferred to the thermal store of the surroundings.
The rest of the energy is transferred by sound.
What is the efficiency of the engine?
65%65\%65%
10%10\%10%
75%75\%75%
25%25\%25%
50 exam-style questions on OCR GCSE Physics 7.2 Power and efficiency, covering 7.2.1 Dissipation of energy, 7.2.2 Energy transfers in domestic devices, 7.2.3 Power ratings of domestic appliances, 7.2.4 Efficiency of energy transfers, 7.2.5 Ways to increase efficiency, 7.2.6 Reducing unwanted energy transfers, and 7.2.7 Thermal conductivity and the cooling of buildings. Each one has a worked solution and a mark scheme showing where the marks go.