A circular platform can rotate freely about a pivot at its centre. Three forces act on the platform.
| Force | Force in N | Perpendicular distance from the pivot to the line of action in m | Direction of moment |
|---|---|---|---|
| P | 90 | 0.40 | clockwise |
| Q | 70 | 0.30 | clockwise |
| R | 100 | 0.45 | anticlockwise |
A fourth force produces an anticlockwise moment. Its line of action is at a perpendicular distance of 0.60 m from the pivot.
Calculate the magnitude of the fourth force needed to balance the platform.
Instead, a fourth force of 25 N produces an anticlockwise moment at a perpendicular distance of 0.40 m from the pivot.
Explain whether the platform is balanced and, if it is not balanced, predict the direction in which it will begin to rotate.
124 exam-style questions on AQA GCSE Physics 5.4 Moments, levers and gears, covering 5.4 Moments, levers and gears. Each one has a worked solution and a mark scheme showing where the marks go.