CMC Medical CMC-Medical VELLORE Solved Paper-2012

  • question_answer
    If the kinetic energy of a body is decreased by 36%, then its momentum is decreased by

    A)  6%                                        

    B)  8%

    C)  20%                                      

    D)  36%

    Correct Answer: C

    Solution :

                    The momentum and kinetic energy is related by \[p=\sqrt{2mE}\] \[\therefore \]  \[p\propto \sqrt{E}\] According to question, kinetic energy becomes 64% of the original \[\therefore \]  \[\frac{{{p}_{2}}}{{{p}_{1}}}=\sqrt{\frac{{{E}_{2}}}{{{E}_{1}}}}\]                 \[=\sqrt{\frac{64E}{100E}}\]                 \[=\frac{8}{10}=0.8\] \[\Rightarrow \] \[{{p}_{2}}=0.8\,p\] \[\therefore {{p}_{2}}=80\,%\] of original value i.e., decrease in momentum is 20%.


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