# Explain why an object moving with constant speed along a curved path must be accelerating.

> IB DP Physics Standard Level (2023 syllabus) — A.1 Kinematics · Explain · 4 marks

## Mark scheme (4 marks)

1. Velocity is a vector quantity, so it has both magnitude and direction.
2. As the object moves along a curved path, the direction of its velocity continuously changes.
3. A change in velocity (whether in magnitude or direction) constitutes acceleration.
4. Therefore, even though speed is constant, a change in the direction of velocity means a non-zero acceleration exists.

## Key terms

- [speed](https://www.gradenine.co.uk/glossary/speed)
- [curved path](https://www.gradenine.co.uk/glossary/curved-path)

## Related

- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](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/explain-why-an-object-moving-with-74088437) · Published by Druglandscape Ltd.