# A washing machine transfers electrical energy to clean clothes. Explain why the washing machine is not 100% efficient, and describe what happens to the energy that is not usefully transferred.

> Eduqas GCSE Physics — 1.6 Distance, speed and acceleration · Explain · 4 marks

> A washing machine has a power rating of 2 kW. During a wash cycle, only some of the electrical energy input is usefully transferred to the clothes and water.

## Mark scheme (4 marks)

1. The washing machine produces waste energy transfer(s) / not all energy input is usefully transferred
2. Energy is wasted as heat/thermal energy due to friction in moving parts (e.g. drum motor / bearings)
3. Energy is also wasted as sound energy (e.g. vibration of the drum/motor)
4. The waste energy is transferred to the surroundings / dissipated, consistent with the conservation of energy (energy cannot be created or destroyed)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-washing-machine-transfers-electrical-energy-c9d0266d) · Published by Druglandscape Ltd.