Question

A man pulls 40 kg crate through 20 m across a level floor with a rope which makes 30 with the horizontal. He exerts a force of 150 N on the rope. Find the work done.

Answer 1

The horizontal component of the force $F_h=F\cos 30=150\times \frac{\sqrt{3}}{2}=75\sqrt{3}N$

As force due to gravity is downward so the work done causes by only horizontal force.

Work done $W=F_{h}d=75\sqrt{3}\times 20=1500\sqrt{3}J$