Question

Fig. shows a heavy roller, with its axle at O, which is to be raised on a pavement PQ. If there is friction between the roller and pavement, show by an arrow on the diagram the point of application and the direction of force to be applied.

Answer 1

The force should be applied at the axle O in a direction perpendicular to OP.

Since OP is horizontal in the figure, the force should be directed vertically upward through O.

This gives the maximum turning effect about the edge P, helping the roller rise onto the pavement.