# A person stands on a set of bathroom scales inside a lift. The scales show a reading greater than the person's actual weight when the lift begins to move upwards from rest. Explain why the scales show a higher reading than the person's actual weight during this upward acceleration.

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

## Mark scheme (5 marks)

1. The person (and lift) is accelerating upwards
2. A resultant / net force is needed to cause this upward acceleration
3. The normal contact force (reaction force from the scales) acting on the person is greater than the person's weight
4. The scales measure the normal contact force / reaction force acting on them, not the person's actual weight
5. Because the contact force is greater than the weight, the scales display a higher reading than the person's true weight

## Key terms

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

## 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-person-stands-on-a-set-dbe001ef) · Published by Druglandscape Ltd.