# A swimming pool uses an electric pump to circulate water through a heating system. The pump transfers electrical energy, but not all of this energy is used to move the water. Some energy is dissipated as heat in the pump's motor and some is lost as sound. Explain how the efficiency of the pump could be improved, and describe what is meant by efficiency in this context.

> OCR GCSE Physics A: Gateway Science (J249) — P5.2 Power and efficiency · Explain · 4 marks

> A leisure centre manager notices that the pool pump becomes very warm during operation and makes a noticeable humming sound. She wants to improve the system so that more of the electrical energy input is used to move the water rather than being wasted.

## Mark scheme (4 marks)

1. Efficiency is the ratio of useful output energy transfer to total energy input
2. Lubrication of moving parts in the pump reduces friction, which reduces heat loss / waste energy transfer
3. Reducing the current through the motor decreases energy lost as heat in the wires / motor
4. Recycling or reducing waste energy transfer (heat/sound) means more of the input energy becomes useful output, increasing efficiency

## Key terms

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

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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-swimming-pool-uses-an-electric-212fef8d) · Published by Druglandscape Ltd.