# A rowing boat moves at a constant velocity across a still lake. The rower then stops rowing and the boat gradually slows down and comes to rest. Explain why the boat travels at a constant velocity whilst the rower is rowing, and why the boat decelerates after the rower stops.

> Eduqas A-Level Physics — 1.2 Forces and Newton's laws · Explain · 5 marks

## Mark scheme (5 marks)

1. At constant velocity, the driving force from the oars equals the resistive forces (water resistance / drag / friction)
2. Balanced / equal forces mean there is no resultant force
3. Newton's first law: an object continues at constant velocity when there is no resultant force acting on it
4. When the rower stops, the driving force is removed but water resistance / drag still acts on the boat
5. There is now a resultant force (in the direction opposing motion) so the boat decelerates / Newton's second law: resultant force causes acceleration / deceleration

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level 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-rowing-boat-moves-at-a-663ed79d) · Published by Druglandscape Ltd.