1. [-/1 Points] DETAILS SCALCET9 6.4.AE.001. Example 1 Video Example () (a) How much work is done in lifting a 1.4-kg book off the floor to put it on a desk that is 0.8 m high? Use the fact that the acceleration due to gravity is g = 9.8 m/s. (b) How much work is done in lifting a 24-lb weight 5 ft off the ground? Solution (a) The force exerted is equal and opposite to that exerted by gravity, so the force is F = m = mg = (1.4)(9.8) = N dt 2 and then the work done is W = Fd = (0.8) = (b) Here the force is given as F = 24 lb, so the work done is W = Fd = 24 . 5 = ft - lb . Notice that in part (b), unlike part (a), we did not have to multiply by g because we were given the weight (which is a force) and not the mass of the object. Need Help? Read It