Question

A crowbar is 3 metres long and has its pivot 30 cm from one end. A force of 3000 N is applied to the end closest to the pivot. What effort must be applied to the other end of the crowbar to keep it in equilibrium

Answer 1

Take moments about the pivot. Convert 30 cm = 0.30 m, so the distances are 0.30 m and 3.00 − 0.30 = 2.70 m.

For equilibrium: 3000 N × 0.30 m = E × 2.70 m
=> E = (3000 × 0.30) / 2.70 = 900 / 2.70 ≈ 333.3 N.

So an effort of about 333 N (opposite direction) is required.