# A vehicle travelling at high speed is involved in a collision and comes to a sudden stop. The vehicle is fitted with a crumple zone and the driver is wearing a seat belt. Explain how these two safety features reduce the risk of serious injury to the driver during the collision.

> Eduqas A-Level Physics — 4.2 Kinetic theory and gases (A-Level only) · Explain · 5 marks

## Mark scheme (5 marks)

1. Both the crumple zone and seat belt increase the time over which the momentum change occurs (during the collision)
2. The driver's momentum must change (from a high value to zero) during the collision
3. Force is equal to the rate of change of momentum, so a longer time means a smaller force
4. The crumple zone compresses during the collision, increasing the stopping time/distance for the vehicle
5. The seat belt holds the driver back so they decelerate with the car rather than hitting the interior, further spreading the momentum change over time

## Key terms

- [crumple zone](https://www.gradenine.co.uk/glossary/crumple-zone)
- [seat belt](https://www.gradenine.co.uk/glossary/seat-belt)

## Related

- [Revision notes for Eduqas A-Level Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-vehicle-travelling-at-high-speed-b4d74f19) · Published by Druglandscape Ltd.