# A worker uses a machine to lift heavy crates from the ground onto a shelf. The machine takes longer than expected to complete the task. Explain what is meant by the power of the machine and describe what effect the longer time taken has on the power of the machine, assuming the same crates are lifted to the same shelf.

> Edexcel GCSE Physics (1PH0) — 8.1 Energy — forces doing work · Explain · 4 marks

## 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 (or energy transferred) by the time taken
3. The work done (energy transferred) lifting the crates to the shelf remains the same / is unchanged
4. Because time taken increases (and work done stays the same), the power of the machine decreases

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](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-worker-uses-a-machine-to-2dec7c74) · Published by Druglandscape Ltd.