A) 25 J
B) 50 J
C) 75 J
D) 100 J
Correct Answer: C
Solution :
\[Velocity\text{ }\left( v \right)=\frac{dx}{dt}=\frac{d}{dt}\left( 3{{t}^{2}}+4t+5 \right)=6t+4\] Acceleration is a \[a=\frac{dv}{dt}=\frac{d}{dt}\left( 6t+4 \right)=6\,m{{s}^{-2}}\] Therefore, applied force is \[F=ma=0.5\times 6=3N\] Now\[t\,\,=\,\,2s\], the distance moved is \[x=3\times {{\left( 2 \right)}^{2}}+4\times 2+5=25\,m\] \[\therefore \,\,\,Work\text{ }done\text{ }W=Fx=3\times 25=75\,J.\] Hence the correct choice is [c].You need to login to perform this action.
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