A block of mass 30 kg is pulled up by a rope as shown in Fig. with a constant speed by applying a force of 200 N parallel to the slope. A and B are initial and the final positions of the block. Calculate:
(a) the work done by the force in moving the block A to B,
(b) the potential energy gained by the block,
(c) account for the difference in work done the force and the increase in potential energy of the block.

Answer

A, B, C, D

Explanation

Here, m = 30kg, F = 200N, s =AB =3m, h =1.5m
(a) Work done by the force in moving the block form A to B, i.e., W =F s =(200N)(3m) =60J
(b) Potential energy gained by the block `E_p =mgh = (30kg)(10m//s^2)(1.5m) =450J`
(c ) The difference (600J - 450 J =150J) is used in doing work against friction between the block and the
slope. This energy is converted into heat.