# A ice skater glides across a smooth ice rink at a constant velocity. She then pushes off a barrier at the edge of the rink. Explain, using Newton's laws, why the skater accelerates away from the barrier after pushing off, and what happens to her velocity once she stops pushing and there is no resultant force acting on her.

> OCR GCSE Physics A: Gateway Science (J249) — P2.2 Newton's laws · Explain · 4 marks

> An ice skater is practising on a rink. The ice is smooth enough that friction and air resistance can be considered negligible.

## Mark scheme (4 marks)

1. When she pushes on the barrier, the barrier exerts an equal and opposite force back on the skater (Newton's Third Law)
2. This reaction force is the resultant force acting on the skater, causing her to accelerate (Newton's Second Law)
3. Once she stops pushing there is no resultant force acting on her
4. She continues to move at a constant velocity (same speed and direction) — Newton's First Law

## Key terms

- [resultant force](https://www.gradenine.co.uk/glossary/resultant-force)
- [constant velocity](https://www.gradenine.co.uk/glossary/constant-velocity)

## 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/a-ice-skater-glides-across-a-11be6045) · Published by Druglandscape Ltd.