# A firefighter climbs a vertical ladder to reach the top floor of a burning building. A second firefighter, who has a greater body mass, climbs the same ladder to the same height in a shorter time. Explain why the second firefighter has a greater power output than the first, even though both firefighters do work against gravity.

> Pearson Edexcel International GCSE Physics (4PH1) — 4.2 Work and power · Explain · 4 marks

> Two firefighters climb an identical vertical ladder. Firefighter A has a mass of 70 kg and reaches the top in 12 s. Firefighter B has a mass of 90 kg and reaches the top in 8 s.

## Mark scheme (4 marks)

1. Work done equals force multiplied by distance (W = Fd), and a greater mass means a greater gravitational force acting downwards, so Firefighter B does more work climbing the same height.
2. Power is the rate at which work is done (power = work done ÷ time taken), so a greater amount of work done in a shorter time gives a larger power output.
3. Firefighter B does more work than Firefighter A (because greater mass → greater weight → greater work done against gravity over the same height).
4. Firefighter B also takes less time, so both a larger numerator (work done) and a smaller denominator (time) result in a larger value of power.

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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-firefighter-climbs-a-vertical-ladder-9d5de161) · Published by Druglandscape Ltd.