# A student stretches a copper wire by hanging different weights from it. At first, the wire returns to its original length when the weights are removed. After a certain weight is added, the wire does not return to its original length when that weight is removed. Explain what has happened to the copper wire at this point and describe the difference between the wire's behaviour before and after this change.

> AQA A-Level Physics (7408) — 3.4.2 Materials · Explain · 5 marks

## Mark scheme (5 marks)

1. The wire has been stretched beyond its elastic limit / limit of proportionality
2. Before this point the wire showed elastic behaviour / elastic deformation
3. Elastic behaviour means the wire returned to its original shape / length after the force was removed
4. After this point the wire showed inelastic / plastic deformation
5. Inelastic deformation means the wire has a permanent change in shape / does not return to its original length after the force is removed

## Related

- [Revision notes for AQA A-Level Physics (7408)](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-student-stretches-a-copper-wire-b377fe27) · Published by Druglandscape Ltd.