A force acts on a 1 kg body such that the distance moved varies as a function of time according to the equation X=4t2+3t+5, where X is in the meters and t in sec. What is the work done by the force in first three seconds?
A
120 J
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B
240 J
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C
320 J
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D
360 J
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Solution
The correct option is D 360 J Given m=1Kg, t=3s and the distance moved varies as function of time according to the equation, X=4t2+3t+5 For t=3 X=4(3)2+3(3)+5 X=50m And For t=0, X=4(0)2+3(0)+5 X=5m ∴ΔX=45m Now, force is given by F=ma=md2Xdt2 F=1×d2(4t2+3t+2)dt2 F=8 now, W=F.ΔX=(8)(45)=360J