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EXAMPLE Calculate the work done in raising a stone ofmass 5 kg and specific gravity 3, lying at the bed of a lakethrough a height of 5 m |
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Answer» ratio of density of body : water = 3:1 , so, water will exert a force of Dw*v*g and gravity force will be Db*v*g Fw/Fg = 1/3 => Fw = Fg/3 Net force acting downward = Fg -Fg/3 = 2Fg/3 = 2*mg/3 so, work done will be net force × displacement= 2*mg/3*5= 2*5*10*5/3= 500/3 J |
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