BCECE Engineering BCECE Engineering Solved Paper-2004

  • question_answer
    If the momentum of body is increased by 100%, then the percentage increase in the kinetic energy will be:

    A)  330%                                   

    B)         225%

    C)         200%                                   

    D)         300%

    Correct Answer: D

    Solution :

    Kinetic energy is related to momentum  through the relation \[K=\frac{{{p}^{2}}}{2m}\] or            \[\frac{{{K}_{2}}}{{{K}_{1}}}=\frac{p_{2}^{2}}{p_{1}^{2}}\]                           ?(i) Given, \[{{p}_{1}}=p,{{p}_{2}}=p+\frac{p\times 100}{100}=p+p=2p,\] \[{{K}_{1}}=K\] \[\therefore \]  \[\frac{{{K}_{2}}}{K}=\frac{{{(2p)}^{2}}}{{{p}^{2}}}=\frac{4{{p}^{2}}}{{{p}^{2}}}\] Increase in kinetic energy \[\frac{{{K}_{2}}-K}{K}=\frac{4{{p}^{2}}-{{p}^{2}}}{{{p}^{2}}}=3\] Hence, percentage increase in kinetic energy \[\left( \frac{{{K}_{2}}-K}{K} \right)\times 100=(3\,\times \,100)%\]         \[=300%\]


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