Question Constellation Sign up for free AQA · GCSE · Physics · Higher
Rocket weight during upward acceleration
The rocket has a passenger module and a propulsion module.
The propulsion module burns a large volume of fuel.
The rocket accelerated upwards from the ground until it reached a height of 40 km.
Explain how the weight of the rocket changed as it accelerated upwards.
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Marking points
- 1 Relates weight to mass and gravitational field strength, for example W = mg.
- 2 Explains that mass decreases as fuel burns or that gravitational field strength decreases with height.
- 3 Concludes that the rocket's weight decreases.
Full-mark answer
Weight is given by W = mg. As the rocket rises it burns fuel, so its mass decreases; gravitational field strength also decreases with height. Therefore the rocket's weight decreases as it accelerates upwards.
Why this answer loses marks
The weight increases because the rocket is accelerating upwards.
Weight depends on mass and gravitational field strength, not on the direction of acceleration. Fuel use reduces mass, and gravitational field strength decreases with height, so weight decreases.