WB JEE Medical WB JEE Medical Solved Paper-2010

  • question_answer
    If momentum is increased by 20%, then kinetic energy increases by

    A)  48%                                      

    B)  44%

    C)  40%                                      

    D)  36%

    Correct Answer: B

    Solution :

                     The kinetic energy is given by\[KE=\frac{{{p}^{2}}}{2m}\] So,          \[\Delta KE=\frac{2p\Delta p}{2m}=\frac{p\Delta p}{m}\] \[\Rightarrow \]               \[\frac{\Delta KE}{KE}=\frac{p\Delta p}{m}\times \frac{2m}{{{p}^{2}}}=\frac{2\Delta p}{p}\] Since momentum p increases by 20%, so the final momentum becomes 1.2 p. Hence,   \[K{{E}_{final}}=\frac{{{(1.2p)}^{2}}}{2m}=1.44\,\frac{{{p}^{2}}}{2m}=1.44\,KE\] So, % change in \[KE=44%\]


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