Question

a) Suppose a cargo truck's rope and puiley system lowers a cocoa bag, having a total mass of 90.0 kg, down a 60.0° slope at constant speed. The coetficient of friction between the bag

and the ground is 0.100.

i) How much work is done by friction as the bag moves 30.0 m along the hill? 

i) How much work is done by the rope on the bag in this distance? 

Answer 1

The work done by friction is

$$W_f=fx=\mu Nx=\mu·mg\sin\theta·x=2290\text{ J}.$$

The work done by the rope is

$$W_r=-Tx=-\mu mg·x=-2290\text{ J}.$$