NEET Sample Paper NEET Sample Test Paper-21

  • question_answer A body having moment of inertia about its axis of rotation equal to \[3\text{ }kg-{{m}^{2}}\]is rotating with angular velocity equal to 3 rad/s. Kinetic energy of this rotating body is the same as that of body of mass 27 kg moving with a speed of

    A)  1.0 m/s                       

    B)  0.5 m/s           

    C)    1.5 m/s            

    D)    2.0 m/s

    Correct Answer: A

    Solution :

    Kinetic energy of rotating body \[=\frac{1}{2}I{{\omega }^{2}}=\frac{1}{2}\times 3\times {{3}^{2}}=13.5\,J\] Kinetic energy of translating body \[=\frac{1}{2}m{{u}^{2}}\] \[\therefore \]\[\frac{1}{2}m{{u}^{2}}=13.5\]or \[\frac{1}{2}\times 27{{u}^{2}}=13.5\]or \[u=1\,m/s.\]

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