JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Question Bank Conservation of Energy and Momentum

  • question_answer
    If momentum is increased by 20%, then K.E. increases by             [AFMC 1997; MP PMT 2004]

    A)                 44%       

    B)                 55%

    C)                 66%       

    D)                 77%

    Correct Answer: A

    Solution :

                        \[E=\frac{{{P}^{2}}}{2m}.\] If m  is constant then \[E\propto {{P}^{2}}\]                 Þ\[\frac{{{E}_{2}}}{{{E}_{1}}}={{\left( \frac{{{P}_{2}}}{{{P}_{1}}} \right)}^{2}}={{\left( \frac{1.2P}{P} \right)}^{2}}=1.44\]                 Þ \[{{E}_{2}}=1.44{{E}_{1}}={{E}_{1}}+0.44{{E}_{1}}\]                 \[{{E}_{2}}={{E}_{1}}+44%\] of \[{{E}_{1}}\]                 i.e. the kinetic energy will increase by 44%


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