# A steel ball bearing is released from rest and falls through a tall cylinder of thick oil. Describe how the speed and acceleration of the ball bearing change from the moment it is released until it reaches terminal velocity.

> Cambridge International IGCSE Physics (0625) — 1.2 Motion · Describe · 4 marks

## Mark scheme (4 marks)

1. The ball bearing accelerates (from rest) / speed increases after release
2. As speed increases, liquid resistance increases
3. The resultant force decreases, so acceleration decreases
4. Terminal velocity is reached when weight equals liquid resistance / when resultant force is zero, so acceleration is zero and speed is constant

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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-steel-ball-bearing-is-released-16549d1f) · Published by Druglandscape Ltd.