A uniform barrier arm is horizontal and can rotate about a pivot. A warning lamp is fixed to the right-hand end of the arm. A counterweight can slide along the part of the arm to the left of the pivot.
| Quantity | Value |
|---|---|
| Length of barrier arm | 4.80 m |
| Position of pivot, measured from the left-hand end | 0.80 m |
| Weight of barrier arm | 180 N |
| Weight of warning lamp | 30 N |
| Position of warning lamp, measured from the left-hand end | 4.80 m |
| Weight of counterweight | 680 N |
Give the perpendicular distance from the pivot to the line of action of the weight of the barrier arm.
Calculate the total clockwise moment about the pivot due to the barrier arm and the warning lamp.
The counterweight is positioned so that the barrier arm is balanced horizontally.
Calculate the position of the counterweight, measured from the left-hand end of the barrier arm.
The warning lamp is replaced by a heavier lamp weighing 70 N, fixed at the same position. The counterweight can be moved as far as the left-hand end of the barrier arm. Explain whether the counterweight can balance the barrier arm with this lamp.
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.