A battery-powered toy car runs along a flat floor until its battery goes flat. The car then stops.
Where is most of the energy that was in the chemical store of the battery now?
In the kinetic store of the toy car
In the gravitational store of the toy car
In the thermal store of the surroundings
Destroyed by friction with the floor
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.