a crane lifts load of 500kg mass to a distance f 20m in 10s at a constant velocity. how much work is done?
work done(W) is given by the change in the potential energy(P.E). here, initial P.E = 0. final P.E = mgh = (500)(10)(20) = 100000 J =100 KJ (kilo joules) therefore work done = 100 KJ. here distance means vertical height.But if the crane takes the load parallel to the ground ,then work done will be zero.Time is given here to calculate the power of the crane given by work/time = 10 KW(kilo watts).
