JEE Main & Advanced JEE Main Solved Paper-2017

  • question_answer
    A time dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest, the work done by the force during the first 1 sec. will be:                                           JEE Main Solved Paper-2017

    A)  9 J                                         

    B)  18 J

    C)  4.5 J                     

    D)  22 J

    Correct Answer: C

    Solution :

     \[F=6t=ma\]                 \[\Rightarrow \]               \[a=6t\] \[\Rightarrow \]               \[\frac{dv}{dt}=6t\] \[\int_{0}^{v}{dv}=\int_{0}^{1}{6t}\,dt\] \[v=(3{{t}^{2}})_{0}^{1}=3\,m/s\] From work energy theorem \[{{W}_{F}}=\Delta K.E=\frac{1}{2}m\left( {{v}^{2}}-{{u}^{2}} \right)\] \[=\frac{1}{2}(1)(9-0)=4.5\,J\]


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