# A crane lifts a steel beam vertically upwards at a steady speed. The crane's motor transfers 18 000 J of energy to the beam in 12 seconds. Explain what is meant by the power of the crane's motor and describe how the values given allow you to determine it, stating whether this power output is relatively large or small compared to a typical household light bulb rated at 60 W.

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

> A crane on a construction site lifts a steel beam vertically upwards at a steady speed. The crane's motor transfers 18 000 J of energy to the beam in 12 seconds.

## Mark scheme (4 marks)

1. Power is the rate at which energy is transferred (or the rate at which work is done)
2. Power is calculated by dividing the work done (energy transferred) by the time taken
3. Correct power value stated as 1 500 W
4. 1 500 W is much greater than 60 W, so the crane's motor has a much larger power output than the light bulb

## Key terms

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

## 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-crane-lifts-a-steel-beam-f87ed18b) · Published by Druglandscape Ltd.