# A student sets up a ripple tank to study water waves. The student notices that a piece of cork floating on the surface bobs up and down as waves pass beneath it, but does not travel across the tank. Explain what this observation tells us about the nature of water waves, and describe the difference between transverse and longitudinal waves.

> WJEC A-Level Physics (Wales) — 2.4 The nature of waves · Explain · 5 marks

> Water waves in a ripple tank cause a floating cork to oscillate up and down, but the cork stays in roughly the same horizontal position even as waves travel across the surface.

## Mark scheme (5 marks)

1. The cork moving up and down (but not progressing) shows that the water particles oscillate/vibrate but do not travel with the wave / energy is transferred but matter is not
2. In a transverse wave, the oscillation/vibration of particles is perpendicular (at right angles) to the direction of wave travel
3. Water waves (in the ripple tank) are transverse waves / the up-and-down motion of the cork is consistent with a transverse wave
4. In a longitudinal wave, the oscillation/vibration of particles is parallel to (along the same line as) the direction of wave travel
5. Longitudinal waves consist of compressions and rarefactions / regions where particles are pushed together (compressions) and spread apart (rarefactions)

## Key terms

- [longitudinal wave](https://www.gradenine.co.uk/glossary/longitudinal-wave)

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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-sets-up-a-ripple-2760740a) · Published by Druglandscape Ltd.