# Explain why crumple zones and seat belts are both used as safety features in modern cars to protect occupants during a collision.

> OCR GCSE Physics A: Gateway Science (J249) — P8 Global challenges · Explain · 4 marks

> During a crash test, a car travelling at high speed collides with a barrier and comes to a sudden stop. Engineers analyse the forces experienced by the dummy occupants inside the car.

## Mark scheme (4 marks)

1. Crumple zones increase the time over which the momentum change occurs (during the collision)
2. Because the time is increased, the force experienced by the occupants is reduced
3. Seat belts increase the time over which the occupant's momentum change occurs (by stretching slightly)
4. This reduces the force experienced by the wearer, preventing serious injury

## 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 OCR GCSE Physics A: Gateway Science (J249)](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/explain-why-crumple-zones-and-seat-cef4c631) · Published by Druglandscape Ltd.