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A body of mass 3 kg is under a constant force which causes a displacement s in metres in it, given by the relation `s=1/3t^2` , where t is in seconds. Work done by the force in 2 seconds is:-A. `5/19J`B. `3/8J`C. `8/3J`D. `19/5J` |
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Answer» Correct Answer - C By using work energy theorem `W=DeltaKE=(1)/(2) mv_(2)^(2)-(1)/(2) mv_(2)^(2)` Now`s=(1)/(3)t^(2) impliesv=(2)/(3)t` `impliesv_(1)=0,v_(2)=(2)/(3)xx2=(4)/(3)ms^(-1)` Therefore W`(1)/(2)xx3((4)/(3))^(2)-(1)/(2)xx3xx(0)^(2)=(8)/(3)J` |
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