A body of mass 5 kg is lifted vetically at a constant velocity of 12m. Calculate-

1.force applied.

2.work done in lifting the body.

3.what happens to the work performed?

The force applied on the body is equal to its weight = mg     (as body moving with constant velocity)
1) force applied = mg = 5*10 = 50 N
2) Net work done on the body is zero as net force is zero.
     
3)Work done by lifting force is cancelled by work done by gravitaional force.