# A car is travelling along a straight, level road at a constant speed. Explain why the car continues at constant speed even though the engine is providing a driving force.

> Eduqas GCSE Physics — 2.3 Forces and motion · Explain · 4 marks

> A car engine produces a driving force to keep the car moving at a steady speed along a flat road.

## Mark scheme (4 marks)

1. At constant speed, the forces on the car are balanced (resultant force is zero)
2. There is a resistive force / friction / air resistance acting on the car in the opposite direction to motion
3. The driving force equals the resistive force / friction / air resistance in size
4. According to Newton's first law, an object continues at constant velocity when the resultant force is zero / no resultant force means no change in motion

## Key terms

- [driving force](https://www.gradenine.co.uk/glossary/driving-force)
- [constant speed](https://www.gradenine.co.uk/glossary/constant-speed)

## Related

- [Revision notes for Eduqas GCSE 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-car-is-travelling-along-a-451b48b5) · Published by Druglandscape Ltd.