# A wind-up toy robot is wound up tightly and then released on a rough carpet. As it moves, the robot gradually slows down and stops. Explain the energy transfers that take place from the moment the robot is released until it stops completely.

> Eduqas A-Level Physics — 1.3 Energy concepts · Explain · 5 marks

## Mark scheme (5 marks)

1. The wound-up spring stores elastic potential energy
2. As the robot moves, elastic potential energy is transferred to kinetic energy
3. Friction acts between the robot and the carpet, causing a waste energy transfer
4. Kinetic energy is transferred to thermal energy (heat) in the surroundings / robot and carpet warm up
5. Energy is conserved throughout — the total energy at the end equals the elastic potential energy at the start, consistent with conservation of energy

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-wind-up-toy-robot-is-wound-c7c65545) · Published by Druglandscape Ltd.