# Explain why a car travelling at a higher speed takes a longer distance to stop when the driver applies the brakes, compared with the same car travelling at a lower speed.

> AQA A-Level Physics (7408) — 3.4.1 Mechanics · Explain · 5 marks

> A driver sees a hazard in the road and applies the brakes. The car decelerates and eventually stops.

## Mark scheme (5 marks)

1. Thinking distance is the distance travelled during the driver's reaction time
2. At a higher speed the car travels further during the reaction time, so thinking distance is greater
3. The car has more kinetic energy at a higher speed
4. The braking force must do more work to remove the extra kinetic energy
5. Therefore the total stopping distance (thinking distance + braking distance) is greater at higher speed

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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