# A student wants to estimate the power output of a person walking up a flight of stairs. Explain how the student could arrive at a reasonable estimate, including any values they would need to use.

> AQA A-Level Physics (7408) — 3.1.3 Estimation of Physical Quantities · Explain · 5 marks

## Mark scheme (5 marks)

1. Estimate a reasonable value for the mass of a person (e.g. 60–80 kg)
2. Estimate a reasonable value for the height of the flight of stairs (e.g. 3–5 m)
3. Estimate a reasonable time to climb the stairs (e.g. 5–10 s)
4. State that gravitational potential energy gained equals mass × gravitational field strength × height (or work done = mgh), using g ≈ 10 N/kg
5. State that power = energy / time (or work done / time), leading to a reasonable calculated estimate (e.g. 200–700 W)

## Key terms

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

## 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-student-wants-to-estimate-the-a4d8b835) · Published by Druglandscape Ltd.