In figure (i) the man walks2 m carrying a mass of 15 kg on his hands .In figure (ii) , he walks the same distancepullingthe ropebehind him . The ropegoesover a pulley , and a mass of 15 kg hangsat its other end . In which case is the work done greater ?

In figure (i) the man walks2 m carrying a mass of 15 kg on his hands .

1.	In figure (i) the man walks2 m carrying a mass of 15 kg on his hands .In figure (ii) , he walks the same distancepullingthe ropebehind him . The ropegoesover a pulley , and a mass of 15 kg hangsat its other end . In which case is the work done greater ?
Answer» Solution :In figure (a) force is applied on the mass , BYTHE manin vertically upward direction but distanceis movedalongthe horizontal.Sothe 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 tensionforce EXERTS in the rope after pulley and if body of mass 15 kg makes displacement of 2m . 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)