# A satellite travels at constant speed in a circular orbit around the Earth. Explain why the satellite is accelerating even though its speed does not change, and describe the direction of both the resultant force and the acceleration acting on the satellite.

> Eduqas A-Level Physics — 1.5 Circular motion (A-Level only) · Explain · 5 marks

> Satellites used for communication travel at constant speed in circular orbits above the Earth's surface.

## Mark scheme (5 marks)

1. Velocity is a vector quantity / velocity has both magnitude (speed) and direction
2. The direction of the satellite's motion is continuously changing as it travels around the circular orbit
3. A change in velocity (even at constant speed) means the satellite is accelerating
4. The resultant force acting on the satellite is directed towards the centre of the Earth / towards the centre of the circular orbit
5. The acceleration is also directed towards the centre of the Earth / in the same direction as the resultant force

## Key terms

- [acceleration](https://www.gradenine.co.uk/glossary/acceleration)
- [resultant force](https://www.gradenine.co.uk/glossary/resultant-force)
- [circular orbit](https://www.gradenine.co.uk/glossary/circular-orbit)

## Related

- [Revision notes for Eduqas A-Level Physics](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-satellite-travels-at-constant-speed-5f9eac4f) · Published by Druglandscape Ltd.