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.