# A boat is floating motionless on a still lake. Explain why the boat remains stationary, referring to the forces acting on it.

> Eduqas GCSE Physics — 3.1 Forces and their interactions · Explain · 4 marks

> A wooden boat sits on the surface of a calm lake without moving in any direction.

## Mark scheme (4 marks)

1. There are at least two forces acting on the boat (weight/gravity downwards AND upthrust/buoyancy force upwards)
2. The weight of the boat acts downwards
3. The upthrust from the water acts upwards on the boat
4. The forces are balanced / equal in size, so the resultant force is zero, meaning there is no change in motion

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