# A bicycle tyre is inflated by pumping air into it. The volume of the tyre remains constant. Explain why the pressure inside the tyre increases as more air is pumped in.

> AQA GCSE Physics (8463) — 4.3.3 Particle model and pressure (Phys only) · Explain · 4 marks

## Mark scheme (4 marks)

1. More (air) particles/molecules are present in the same (fixed) volume
2. The particles are in constant random motion and collide with the walls of the tyre
3. More collisions occur per unit time / the frequency of collisions with the walls increases
4. Greater total force acts on the walls per unit area, so pressure increases

## Key terms

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

## Related

- [Revision notes for AQA GCSE Physics (8463)](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-bicycle-tyre-is-inflated-by-fa2b3cdb) · Published by Druglandscape Ltd.