# Explain why a gas in a thermally insulated container rises in temperature when it is rapidly compressed.

> IB DP Physics Standard Level (2023 syllabus) — B.1 Thermal energy transfers · Explain · 4 marks

> A bicycle pump is sealed at its outlet so that no air escapes. The handle is pushed in rapidly, compressing the trapped air.

## Mark scheme (4 marks)

1. Work is done ON the gas by the moving piston/handle during compression.
2. Because the container is thermally insulated, no thermal energy is transferred to or from the surroundings (Q = 0).
3. The internal energy of the gas therefore increases (by an amount equal to the work done on it).
4. Greater internal energy means greater average kinetic energy of the gas molecules, so temperature rises.

## Key terms

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

## Related

- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](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-a-gas-in-a-e31924a7) · Published by Druglandscape Ltd.