# A student stretches a spring by hanging masses from it. The student notices that when the load is small, doubling the load doubles the extension. However, beyond a certain point, doubling the load produces an extension more than double the previous extension. Explain these observations, using the terms limit of proportionality and spring constant in your answer.

> Cambridge International IGCSE Physics (0625) — 1.5 Forces · Explain · 4 marks

## Mark scheme (4 marks)

1. Below the limit of proportionality, extension is directly proportional to the applied force/load
2. The spring constant remains constant/unchanged below the limit of proportionality
3. Beyond the limit of proportionality, extension is no longer directly proportional to the applied force/load
4. Beyond the limit of proportionality, a smaller force/load is needed to produce each unit of extension, so the same doubling of load gives more than double the extension

## Key terms

- [limit of proportionality](https://www.gradenine.co.uk/glossary/limit-of-proportionality)
- [spring constant](https://www.gradenine.co.uk/glossary/spring-constant)
- [extension](https://www.gradenine.co.uk/glossary/extension)

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](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-spring-by-7629fed3) · Published by Druglandscape Ltd.