Determine the force P needed to pull the 50-kg roller Over the smooth step. Take θ = 60°...

Draw the schematic representing the geometry of the segment .

Calculate the angle .

Substitute for and for .

When the roller is moving over the step the reaction exerted by the smooth surface will be zero, at that instant take the moments about point B.

Substitute for , for and for .

Therefore, the force required to pull the 50kg roller over the smooth step is .