# A large stone is lifted from the ground and placed on a high shelf. Explain the energy transfers that take place during this process, and state what happens to the total energy of the stone and its surroundings.

> WJEC A-Level Physics (Wales) — 1.3 Energy concepts · Explain · 5 marks

> A builder lifts a 15 kg stone from the ground and places it on a shelf 2 m above the floor. The builder's muscles do work to raise the stone.

## Mark scheme (5 marks)

1. Work is done on the stone because a force moves it through a distance
2. Chemical energy (in the builder's muscles) is transferred
3. The stone gains gravitational potential energy because it is raised to a greater height
4. Some energy is wasted, transferred to the surroundings as thermal energy / heat (due to friction or heat generated in muscles)
5. The total energy of the stone and its surroundings remains the same, in accordance with the conservation of energy

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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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