A road-safety team measures the stopping distance of a minibus at two different speeds on a dry runway. The driver takes the same time to react in both tests. Nothing that affects braking changes between the tests, so the distance the minibus travels after the brakes are applied can be taken to be proportional to the square of its speed.
| Speed in m/s\mathrm{m/s}m/s | Stopping distance in m\mathrm{m}m |
|---|---|
| 10 | 14 |
| 20 | 44 |
Using this model, what is the braking distance of the minibus at a speed of 25 m/s?
50 m50\ \mathrm{m}50 m
65 m65\ \mathrm{m}65 m
15 m15\ \mathrm{m}15 m
55 m55\ \mathrm{m}55 m
126 exam-style questions on Edexcel GCSE Physics 2.5 Stopping and braking distances, covering 2.5.1 Stopping distance and reaction time, 2.5.2 Factors affecting stopping distance, 2.5.3 Dangers of large decelerations, and 2.5.4 Braking distance and initial speed. Each one has a worked solution and a mark scheme showing where the marks go.