In Figure (i) the man walks 2 m carrying a mass of 15 kg on his hands. In Fig (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?

Asked by Abhisek | 1 year ago |  111

##### Solution :-

Scenario I:

m = 20 kg

Displacement of the object, s = 4 m

W = Fs cosθ

θ = It is the angle between the force and displacement

Fs = mgs cosθ

W = mgs cosθ = 20 x 4 x 9.8 $$cos 90^{\circ}$$= 0

$$( cos 90^{\circ} = 0 )$$

Scenario II:

Mass = 20 kg

S = 4 m

The applied force direction is same as the direction of the displacement.

θ =$$0^{\circ}$$

$$Cos 0^{\circ}= 1$$

W = Fs cosθ

= mgsθ

= 20 x 4 x 9.8 x $$cos 0^{\circ}$$

= 784 J

Thus, the work done is more in the second scenario.

Answered by Pragya Singh | 1 year ago

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