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Calculate work done in raising a stone of mass 5kg and specific gravity 3 lying at the bed of a lake through a height of 4 metre. |
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Answer» Here,`m=5kg`, sp. Gravity `=3,h=4m,W=?` As specify gravity of stone `=("mass of stone in air")/("mass of an equal volume of water")` `:. 3=(5kg)/(m) :. m=(5)/(3)kg` Loss of weight of stone when immersed in water = Weight of water displaced `=(5)/(3)kg` Apparent weight of stone in water `=(5-(5)/(3))kg=(10)/(3)kg` Force required to lift the stone, `F=(10)/(3)xx9.8N` Work done `=Fxxh=(10)/(3)xx9.8xx4=130.7J` |
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