# A student pushes a heavy crate across a warehouse floor at a constant speed. Explain the energy transfers that take place and why the total energy of the system is conserved, even though the crate eventually comes to rest when the student stops pushing.

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

> A warehouse worker applies a steady force to push a heavy wooden crate across a concrete floor. The crate moves at constant speed while being pushed, then slows to a stop the moment the worker stops pushing.

## Mark scheme (5 marks)

1. Work is done on the crate because a force causes it to move through a distance
2. The useful energy transfer is kinetic energy (the crate moves)
3. Friction between the crate and the floor causes a waste energy transfer to thermal energy / heat
4. When the crate stops, all the kinetic energy has been dissipated / transferred to thermal energy of the surroundings
5. Energy is conserved because it is transferred, stored or dissipated but never created or destroyed — the total energy of the closed system remains constant

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-pushes-a-heavy-crate-195045a6) · Published by Druglandscape Ltd.