# A comet travels in a highly elliptical orbit around the Sun. As the comet moves closer to the Sun, its speed increases. Explain why the comet speeds up as it approaches the Sun and why it slows down again as it moves away from the Sun.

> Eduqas GCSE Physics — 10.1 Solar system; stability of orbital motions; satellites · Explain · 4 marks

## Mark scheme (4 marks)

1. The Sun's gravity/gravitational force acts on the comet
2. As the comet moves closer to the Sun, the gravitational force does work on the comet / the gravitational force has a component in the direction of motion, causing it to speed up
3. As the comet moves away from the Sun, the gravitational force acts in the opposite direction to its motion
4. This opposing gravitational force decelerates the comet / causes it to slow down

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-comet-travels-in-a-highly-61ebe202) · Published by Druglandscape Ltd.