# A goalkeeper catches a football that is moving towards them at high speed. The goalkeeper moves their hands backwards as they catch the ball, bringing it to rest over a longer time. Explain, using Newton's laws of motion and the concept of momentum, why moving their hands backwards reduces the force felt by the goalkeeper's hands.

> OCR A-Level Physics A (H556) — 3.5 Newton's laws and momentum · Explain · 5 marks

> When catching a fast-moving ball, experienced goalkeepers are trained to 'give' with the ball rather than catching it with rigid, stationary hands.

## Mark scheme (5 marks)

1. The ball has momentum because it has mass and velocity
2. When the ball is stopped its momentum changes to zero / there is a change in momentum
3. Moving the hands back increases the time taken for the ball to stop
4. By Newton's second law / the relationship between force and momentum, force equals the rate of change of momentum
5. A longer time means a smaller rate of change of momentum, so the force on the hands is smaller

## Key terms

- [momentum](https://www.gradenine.co.uk/glossary/momentum)
- [force](https://www.gradenine.co.uk/glossary/force)

## Related

- [Revision notes for OCR A-Level Physics A (H556)](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-goalkeeper-catches-a-football-that-7c1216e4) · Published by Druglandscape Ltd.