MGIMS WARDHA MGIMS WARDHA Solved Paper-2015

  • question_answer
    A flywheel of moment of inertia \[0.4\text{ }kg-{{m}^{2}}\] and radius 20 cm is free to rotate about a central axis. If a string is wrapped on its circumference and it is pulled with a force of 10 N, then the change in its angular velocity after 4 s will be

    A)  10rad/s                               

    B)  20rad/s

    C)  40rad/s                               

    D)  5rad/s

    Correct Answer: B

    Solution :

                    As the string pulls the wheel,. then torque is given by \[\tau =F\times r=I\alpha =I\frac{{{\omega }_{2}}-{{\omega }_{1}}}{t}\] \[\Rightarrow \]               \[{{\omega }_{2}}-{{\omega }_{1}}=\frac{F\times r\times t}{I}\]                 \[=\frac{10\times 0.2\times 4}{0.4}\] \[\therefore \]  \[\Delta \omega =20\,rad/s\]


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