# A lorry and a small car are both travelling at the same speed on a motorway. The lorry is carrying a full load of heavy goods, while the car has only the driver inside. Both drivers are fully alert and have the same reaction time. Explain why the lorry has a greater stopping distance than the car.

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

> Stopping distance is the sum of thinking distance and braking distance. Braking distance can be affected by the speed and weight of a vehicle, as well as road and tyre conditions.

## Mark scheme (4 marks)

1. Thinking distance is the same for both vehicles
2. The lorry has a greater weight / mass (due to its load)
3. Greater weight / mass means more momentum (at the same speed)
4. Greater momentum means the braking force must act for longer, so the braking distance is greater

## Key terms

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

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-lorry-and-a-small-car-85c717f2) · Published by Druglandscape Ltd.