# Explain why a satellite in a circular orbit around the Earth does not need a continuous thrust force to maintain its orbit.

> AQA GCSE Physics (8463) — 4.8.1 Solar system; stability of orbital motions; satellites (Phys only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Gravity provides a force on the satellite (towards the Earth / centripetal force)
2. This gravitational force continuously changes the direction of the satellite's velocity (without changing its speed)
3. The satellite travels at the correct/orbital speed such that the curvature of its path matches the curvature of the Earth's surface / it keeps falling towards Earth but the Earth curves away
4. There is no air resistance (in space/at that altitude) to slow the satellite down, so no thrust is needed to maintain speed

## Key terms

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

## Related

- [Revision notes for AQA GCSE Physics (8463)](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-satellite-in-a-817e7fb9) · Published by Druglandscape Ltd.