# Explain why the gravitational potential energy of a satellite increases as it moves from a low orbit to a higher orbit, yet the total mechanical energy of the satellite also increases.

> IB DP Physics Standard Level (2023 syllabus) — D.1 Gravitational fields · Explain · 4 marks

> A satellite orbits the Earth in a circular orbit. A rocket burn causes the satellite to move to a higher circular orbit.

## Mark scheme (4 marks)

1. Gravitational potential energy is defined as negative, becoming less negative (increasing towards zero) as the satellite moves further from Earth's centre.
2. The kinetic energy of the satellite decreases as orbital radius increases, because orbital speed decreases with increasing radius.
3. The magnitude of the increase in gravitational potential energy is greater than the magnitude of the decrease in kinetic energy.
4. The rocket burn does work on the satellite, providing the net energy input that raises the total mechanical energy of the satellite.

## Key terms

- [gravitational potential energy](https://www.gradenine.co.uk/glossary/gravitational-potential-energy)
- [total mechanical energy](https://www.gradenine.co.uk/glossary/total-mechanical-energy)

## Related

- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](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-the-gravitational-potential-energy-84624da3) · Published by Druglandscape Ltd.