# A bicycle tyre is pumped up so that it contains more air, but the volume of the tyre stays the same and the temperature does not change. Explain why the pressure inside the tyre increases when more air is added.

> Eduqas GCSE Physics — 2.2 The kinetic theory and gas pressure · Explain · 4 marks

## Mark scheme (4 marks)

1. Adding more air means there are more gas particles/molecules inside the tyre
2. The particles collide with the walls of the tyre more frequently / there are more collisions per second with the tyre walls
3. Pressure is the perpendicular force per unit area acting on the surfaces of the tyre as a result of these collisions
4. Because the volume is constant, the increased number of collisions results in a greater force per unit area, so pressure increases

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](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-pumped-up-832d914c) · Published by Druglandscape Ltd.