# Explain how the acceleration of an object undergoing simple harmonic motion varies with displacement from the equilibrium position, and state what this tells us about the direction of the net force acting on the object.

> IB DP Physics Standard Level (2023 syllabus) — C.1 Simple harmonic motion · Explain · 4 marks

> A mass attached to a horizontal spring oscillates on a frictionless surface. The mass is displaced from its equilibrium position and released.

## Mark scheme (4 marks)

1. The acceleration is directly proportional to the displacement from the equilibrium position.
2. The acceleration is always directed towards the equilibrium position (i.e. opposite in direction to the displacement).
3. Therefore the net (restoring) force is always directed towards the equilibrium position.
4. At maximum displacement (amplitude) the acceleration / net force is greatest, and at the equilibrium position the acceleration / net force is zero.

## Key terms

- [simple harmonic motion](https://www.gradenine.co.uk/glossary/simple-harmonic-motion)
- [equilibrium position](https://www.gradenine.co.uk/glossary/equilibrium-position)
- [displacement](https://www.gradenine.co.uk/glossary/displacement)
- [acceleration](https://www.gradenine.co.uk/glossary/acceleration)

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-acceleration-of-an-1e0bfd4f) · Published by Druglandscape Ltd.