# A student carries a heavy bag up a flight of stairs at a steady speed, then walks along a horizontal corridor at the same steady speed. State what happens to the rate at which the student does work against gravity as they move from the stairs to the corridor, and explain why.

> Cambridge International IGCSE Physics (0625) — 1.7 Energy, work and power · Explain · 4 marks

## Mark scheme (4 marks)

1. The rate of doing work against gravity decreases (to zero) on the corridor
2. On the corridor there is no change in height / the student moves horizontally
3. Work is done (only) when a force moves an object in the direction of the force
4. On the stairs, work is done against gravity because the student (and bag) gain height / move in the direction opposing the gravitational force

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](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-student-carries-a-heavy-bag-7e77426d) · Published by Druglandscape Ltd.