Question

In Fig.(i) the man walks 2 m carrying a mass of 15 kg on his hands. In Fig. 6.13(ii), he walks the same distance pulling the rope behind him. The rope goes over a pulley, and a mass of 15 kg hangs at its other end. In which case is the work done greater?

Answer 1

In the second case
Case (i)
Mass, m = 15 kg
Displacement, s = 2 m

Case (ii)
Mass, m = 15 kg
Displacement, s = 2 m
Here, the direction of the force appliedon the rope and the direction of the
displacement of the rope is same.
Therefore, the angle between them, θ = 0°
Since cos 0° = 1
Work done, W = Fs cosθ = mgs
= 15 x 9.8 x 2 = 294 J
Hence, more work is done in the second case.