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

Explanation

In figure (a) force is applied on the mass , by the man in vertically upward direction but distance is moved along the horizontal .So the angle between gravitational force ( in downward) and distance is `theta = 90^(@)` .Hence work done
`W = Fd cos 90^(@)`
` :. W = 0 `
From figure (b) Man walks horizontally by rope as a result tension force exerts in the rope after pulley and if body of mass 15 kg makes displacement of 2 m . in upward direction then work dne ,
`W = Fd cos 0^(@)`
= Fd
= mgd
` = 15 xx 9.8 xx2 = 294 J `
Hence , work is more in case (b)