# A rocket is launched vertically upwards from the ground. At the moment of launch, the thrust force from the rocket engine is greater than the weight of the rocket. As the rocket rises, the thrust force remains constant but the weight of the rocket decreases. Explain how the motion of the rocket changes from launch until the rocket engine is switched off.

> AQA A-Level Physics (7408) — 3.4.1 Mechanics · Explain · 5 marks

## Mark scheme (5 marks)

1. At launch, the resultant force is upward because thrust is greater than weight
2. An upward resultant force causes the rocket to accelerate upwards
3. As the rocket rises, weight decreases (fuel is used up / rocket loses mass)
4. The resultant force increases as weight decreases (thrust stays constant), so acceleration increases
5. When the engine is switched off, thrust becomes zero so the resultant force acts downward (weight only), causing the rocket to decelerate

## Key terms

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

## Related

- [Revision notes for AQA A-Level Physics (7408)](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-rocket-is-launched-vertically-upwards-e16dc328) · Published by Druglandscape Ltd.