# A sealed syringe contains a fixed quantity of air at room temperature. The plunger is slowly pushed inward, reducing the volume of the air. The temperature of the air stays constant throughout. Explain what happens to the pressure of the air inside the syringe as the volume decreases.

> WJEC GCSE Physics (Wales) — 2.3 Forces and motion · Explain · 4 marks

## Mark scheme (4 marks)

1. The particles collide with the walls of the syringe (more frequently / more often)
2. This is because the same number of particles are now in a smaller volume / space
3. The force on the walls per unit area increases
4. Therefore the pressure increases / pressure and volume are inversely proportional

## Key terms

- [pressure](https://www.gradenine.co.uk/glossary/pressure)
- [volume](https://www.gradenine.co.uk/glossary/volume)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](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-sealed-syringe-contains-a-fixed-b3113a55) · Published by Druglandscape Ltd.