# A battery-powered toy car transfers energy as it moves along a flat surface. Explain why the toy car slows down and eventually stops, referring to useful energy transfer, waste energy transfer, and the conservation of energy.

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

> A battery-powered toy car is switched on and moves along a flat surface. After a short time, the car slows down and stops.

## Mark scheme (5 marks)

1. The battery supplies energy to the motor, which provides a useful energy transfer to kinetic energy (movement) of the car.
2. Friction (between wheels/surfaces) and/or air resistance cause waste energy transfers.
3. The waste energy transfer is to thermal energy (heat), which does not serve the purpose of the system.
4. As the battery runs down, the total energy available to the car decreases, so less energy is available for useful kinetic energy transfer, causing the car to slow down.
5. Energy is conserved throughout — it is not created or destroyed, only transferred; the total energy of the closed system remains constant.

## Key terms

- [useful energy transfer](https://www.gradenine.co.uk/glossary/useful-energy-transfer)
- [waste energy transfer](https://www.gradenine.co.uk/glossary/waste-energy-transfer)
- [conservation of energy](https://www.gradenine.co.uk/glossary/conservation-of-energy)

## Related

- [Revision notes for Eduqas A-Level Physics](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-battery-powered-toy-car-transfers-energy-1f078fb9) · Published by Druglandscape Ltd.