Manipal Medical Manipal Medical Solved Paper-2005

  • question_answer
    A particle performs uniform circular motion with an angular momentum L. If the frequency of particle motion is doubled and its KE is halved, the angular momentum becomes:

    A)  \[2L\]             

    B)  \[4L\]

    C)  \[\frac{L}{2}\]               

    D)  \[\frac{L}{4}\]

    Correct Answer: D

    Solution :

     \[\because \] \[L=m\upsilon r=m{{r}^{2}}\omega \] ?.(i) Also kinetic energy\[K=\frac{1}{2}m{{\upsilon }^{2}}\] Or \[K=\frac{1}{2}m{{(r\omega )}^{2}}=\frac{1}{2}m{{r}^{2}}{{\omega }^{2}}\] \[K=\frac{1}{2}\frac{L}{\omega }{{\omega }^{2}}=\frac{L\omega }{2}\] \[\Rightarrow \] \[L=\frac{2K}{\omega }\] Hence, \[\omega =2\omega \] \[K=\frac{1}{2}K\] \[\therefore \] \[L=\frac{2K}{\omega }=\frac{2\left( \frac{1}{2}K \right)}{2\omega }=\frac{L}{4}\]


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