# A student pushes a heavy crate across a warehouse floor at a constant velocity. Explain why the student must apply a continuous force to keep the crate moving at constant velocity, and describe the energy transfers that occur during this process.

> Eduqas A-Level Physics — 1.1 Basic physics quantities and motion · Explain · 5 marks

> A student pushes a heavy crate across a rough concrete floor. The crate moves at a steady, constant velocity across the floor.

## Mark scheme (5 marks)

1. Friction acts on the crate in the opposite direction to motion (opposing the push)
2. At constant velocity the resultant/net force on the crate is zero, so the applied force must equal the friction force
3. Without a continuous applied force, friction would decelerate/slow the crate (it would not continue at constant velocity)
4. Work is done by the student on the crate / the student transfers energy to the system
5. The energy transferred by the student is dissipated as heat/thermal energy (waste energy transfer) due to friction between the crate and floor

## Key terms

- [constant velocity](https://www.gradenine.co.uk/glossary/constant-velocity)

## 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-student-pushes-a-heavy-crate-b5cfe8ec) · Published by Druglandscape Ltd.