AFMC AFMC Solved Paper-2009

  • question_answer
    If the momentum of a particle is increased by 20%, then its kinetic energy increases by

    A) 44%                                       

    B) 66%

    C) 80%                                       

    D) 30%

    Correct Answer: A

    Solution :

    Energy \[E=\frac{{{p}^{2}}}{2m}\] If m is constant, then \[E\propto {{p}^{2}}\] \[\Rightarrow \]     \[\frac{{{E}_{2}}}{{{E}_{1}}}={{\left[ \frac{{{p}_{2}}}{{{p}_{1}}} \right]}^{2}}\] \[={{\left[ \frac{1.2p}{p} \right]}^{2}}\] \[=1.44\] \[\Rightarrow \]   \[{{E}_{2}}=1.44{{E}_{1}}\]  \[={{E}_{1}}+0.44{{E}_{1}}\]or    \[{{E}_{2}}={{E}_{1}}+44%\]of \[{{E}_{1}}\]ie, the kinetic energy will increase by 44%.       


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