RAJASTHAN PMT Rajasthan - PMT Solved Paper-2002

  • question_answer
    A disc is rolling on an inclined plane- What fraction of its total energy will be as rotational energy :

    A)  4/3                       

    B)         1/3   

    C)  1/2       

    D)         2/3

    Correct Answer: C

    Solution :

                    Linear kinetic energy \[{{K}_{l}}=\frac{1}{2}m{{\upsilon }^{2}}\] \[=\frac{1}{2}m{{\upsilon }^{2}}{{\omega }^{2}}=\frac{1}{2}l{{\omega }^{2}}\] Rotational kinetic energy\[{{K}_{r}}=\frac{1}{2}l{{\omega }^{2}}\] Total kinetic energy                                 \[K={{K}_{l}}+{{K}_{r}}\]                                 \[\begin{align}   & =\frac{1}{2}l{{\omega }^{2}}+\frac{1}{2}l{{\omega }^{2}} \\  & =l{{\omega }^{2}} \\ \end{align}\]                                 \[\frac{{{K}_{r}}}{K}=\frac{1}{2}\]


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