# A natural satellite orbits a planet in a slightly elliptical orbit. Describe how the orbital speed and orbital period of the natural satellite would each change if the satellite moved into a new stable orbit with a greater orbital radius, and explain why a greater orbital radius requires a greater orbital period.

> Pearson Edexcel International GCSE Physics (4PH1) — 8.1 Motion in the universe · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. The orbital speed decreases (when the orbital radius increases)
2. The orbital period increases (when the orbital radius increases)
3. A greater orbital radius means a longer path / greater circumference for one complete orbit
4. The satellite also travels more slowly at the greater orbital radius, so the combination of a longer path and lower speed means the orbital period is greater

## Key terms

- [orbital speed](https://www.gradenine.co.uk/glossary/orbital-speed)
- [orbital period](https://www.gradenine.co.uk/glossary/orbital-period)
- [orbital radius](https://www.gradenine.co.uk/glossary/orbital-radius)
- [natural satellite](https://www.gradenine.co.uk/glossary/natural-satellite)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-natural-satellite-orbits-a-planet-6e6915b7) · Published by Druglandscape Ltd.