# A student pushes a stationary trolley along a smooth, flat surface. After the push, the trolley moves at a steady speed. The student claims that because the trolley is now moving, energy has been created. Explain why the student is wrong, referring to the conservation of energy and describing what happened to the energy during the push.

> WJEC A-Level Physics (Wales) — 1.4 Momentum (A-Level only) · Explain · 5 marks

## Mark scheme (5 marks)

1. Energy cannot be created (or destroyed)
2. The student did work on the trolley / a force moved the trolley through a distance
3. Energy was transferred from the student's (chemical/kinetic) energy store to the trolley
4. The trolley gained kinetic energy / the trolley's kinetic energy store increased
5. The total amount of energy remains the same / energy is only transferred, not created

## Key terms

- [conservation of energy](https://www.gradenine.co.uk/glossary/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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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-pushes-a-stationary-trolley-3f974f95) · Published by Druglandscape Ltd.