RAJASTHAN PMT Rajasthan - PMT Solved Paper-2010

  • question_answer
    The kinetic energy of a body decreases by 36%. The decrease in the momentum is

    A)  36%                                      

    B)  20%

    C)  8%                        

    D)         6%

    Correct Answer: B

    Solution :

    The momentum                 \[p=\sqrt{2mE}\] \[\therefore \]  \[p\propto \sqrt{E}\] In given problem \[KE\] becomes \[64%\] of the original value.                 \[\frac{{{p}_{2}}}{{{p}_{1}}}=\sqrt{\frac{{{E}_{2}}}{{{E}_{1}}}}=\sqrt{\frac{64E}{100E}}=0.8\] \[\Rightarrow \]               \[{{p}_{2}}=0.8\,\,{{p}_{1}}\] \[\therefore \]  \[{{p}_{2}}=80%\]of the original value. \[ie,\]decrease in momentum is\[20%\].


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