# A large lorry and a small car are travelling at the same velocity when they both brake and come to rest. Explain why the lorry has a greater braking distance than the car, even when road conditions and braking force are identical.

> Pearson Edexcel International GCSE Physics (4PH1) — 1.3 Forces, movement, shape and momentum · Explain · 4 marks

> Both vehicles are travelling at 20 m/s on a dry, level road. The braking force applied to each vehicle is the same. The lorry has a mass of 12 000 kg and the car has a mass of 1 200 kg.

## Mark scheme (4 marks)

1. The lorry has a greater mass than the car
2. A greater mass produces a smaller acceleration (deceleration) for the same braking force, as force = mass × acceleration / Newton's second law
3. Because the lorry decelerates more slowly, it takes longer / travels further before reaching zero velocity
4. The lorry has greater momentum (same velocity, larger mass) so a larger change in momentum must occur, requiring more time / distance to stop with the same force

## Key terms

- [braking distance](https://www.gradenine.co.uk/glossary/braking-distance)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-large-lorry-and-a-small-367a2944) · Published by Druglandscape Ltd.