A minibus is tested at two speeds. The driver's reaction time is 0.75 s in both tests, and the road and braking conditions are unchanged.
| Speed in m/s\text{m/s}m/s | Braking distance in m\text{m}m |
|---|---|
| 12 | 12 |
| 24 | 48 |
Calculate the stopping distance of the minibus at each speed.
At 24 m/s, the minibus must stop within 60 m. Calculate the maximum reaction time the driver can have to meet this limit.
Later, the minibus's brakes overheat, and its braking distance from 12 m/s increases to 20 m. A different driver, whose reaction time is 0.40 s, now drives the minibus at 12 m/s.
Determine whether this driver's stopping distance is shorter than the stopping distance at 12 m/s in the first test.
Explain why the stopping distance of the minibus increases by a greater factor than its speed.
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.