# A cyclist travels 12 km due north to reach a town, then immediately turns around and cycles 5 km due south before stopping for a break. Describe the difference between the distance travelled and the displacement of the cyclist at the point where they stop, and explain why knowing only the speed of the cyclist is not enough to fully describe their motion.

> WJEC A-Level Physics (Wales) — 1.1 Basic physics quantities and motion · Describe · 5 marks

## Mark scheme (5 marks)

1. Distance is the total length of the path travelled (12 km + 5 km = 17 km)
2. Displacement is 7 km due north (12 − 5 = 7 km in the original direction)
3. Displacement is a vector quantity — it has both magnitude and direction
4. Speed is a scalar quantity — it only gives the magnitude of how fast the cyclist is moving, with no direction
5. Velocity is needed to fully describe the motion because it includes both speed and direction

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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-cyclist-travels-12-km-due-b2435dce) · Published by Druglandscape Ltd.