Hoist lifts a rock of weight -kg to a height of m.

Newtons second law of motion is given by .

Force exerted is equal and opposite to that exerted by gravity.

Here,  =acceleration of gravity.

Therefore, .

Substitute and in above expression.

N.

Work done formula:

Work done is defined to be the product of the force and distance that the object moves.

.

Here newtons and m.

Work done by hoist is

.  

Work done by hoist is N-m.

Work done by hoist is N-m.