A car makes an emergency stop from 30 m/s. Later it makes an emergency stop from 15 m/s. The braking force is the same each time.
Which statement about the stop from 30 m/s is correct?
The brakes do twice as much work, so they get twice as hot
The brakes do the same work, because the braking force is the same
The brakes do four times as much work, so they get much hotter
The brakes do four times as much work, so the braking force is larger
50 exam-style questions on OCR GCSE Physics 8.1 Physics on the move, covering 8.1.1 Typical everyday speeds, 8.1.2 Typical everyday accelerations, 8.1.3 Ratios, units and rates on the road, 8.1.4 Human reaction times, 8.1.5 Factors affecting stopping distance, 8.1.6 Stopping distances at different speeds, 8.1.7 Dangers of large decelerations, 8.1.8 Estimating forces in road situations, and 8.1.9 Estimating the effects of large accelerations. Each one has a worked solution and a mark scheme showing where the marks go.