# Explain why the pressure inside a sealed gas container increases when the volume of the container is decreased at constant temperature.

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

## Mark scheme (4 marks)

1. The gas molecules are in constant random motion and collide with the walls of the container
2. Decreasing the volume means the molecules have less space / a smaller area to travel through
3. The molecules collide with the walls more frequently / there are more collisions per unit area per unit time
4. More frequent collisions means a greater force per unit area on the walls, so pressure increases

## Key terms

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

## 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/explain-why-the-pressure-inside-a-3fa9c622) · Published by Druglandscape Ltd.