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MGIMS WARDHA MGIMS WARDHA Solved Paper-2009

  • question_answer
    The moment of inertia of a body about a given axis is 1.2 kg-m. Initially the body is at rest. If order to produce a rotational kinetic energy of 1500 J, an angular acceleration of 25 rad/s'2 must be applied about the axis for a duration of

    A)  4s                                          

    B)  2s         

    C)  8s                                          

    D)  10s        

    Correct Answer: B

    Solution :

                     Kinetic energy \[KE=\frac{1}{2}I{{\omega }^{2}}\] \[\Rightarrow \]               \[\omega =\sqrt{\frac{2KE}{I}}=\sqrt{\frac{2\times 1500}{1.2}}\] \[\Rightarrow \]               \[\omega =50\,rad/s\] Now      \[\omega ={{\omega }_{0}}+\alpha t=0+\alpha t\] \[\Rightarrow \]               \[\omega =\alpha t\] \[\therefore \]  \[t=\frac{\omega }{\alpha }=\frac{50}{25}=2s\]


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