Question

A 100 kg block is pulled at a constant speed of 5 m/s across a horizontal force by an applied force of 122 N directed 37 ^o above the horizontal. The rate at which the force does work on the block is.

Answer 1

Given:

$m=100\:\rm kg$

$v=5\:\rm m/s$

$\theta=37^\circ$

$F=122\:\rm N$

The rate of work done (power) is given by

$$P=\frac{W}{t}=\frac{Fd\cos\theta}{t}=Fv\cos\theta$$

$$P=122*5*\cos37^\circ=487\:\rm W$$