# A sealed metal can contains a fixed amount of air. The can is placed in a freezer and left until its temperature drops significantly. Explain why the pressure of the air inside the can decreases as the temperature falls.

> OCR GCSE Physics A: Gateway Science (J249) — P1.3 Pressure · Explain · 4 marks

> A food manufacturer stores sealed metal cans of product in industrial freezers. Engineers notice that the sides of the cans appear to be pushed slightly inward after freezing.

## Mark scheme (4 marks)

1. Decreasing temperature means the particles have less kinetic energy / move more slowly
2. Particles collide with the walls of the can less frequently
3. The collisions with the walls are also less forceful
4. The perpendicular force per unit area on the walls is therefore reduced, so pressure decreases

## Key terms

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

## 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-sealed-metal-can-contains-a-29817fca) · Published by Druglandscape Ltd.