Punjab Medical Punjab - MET Solved Paper-2010

  • question_answer
    A body of mass \[2kg\] makes an elastic collision with another body at rest and continues to move in the original direction with one-fourth its original speed. The mass of the second body which collides with the first body is

    A) \[2kg\]                                 

    B) \[1.2kg\]

    C) \[3kg\]                                 

    D) \[1.5kg\]

    Correct Answer: B

    Solution :

    Conservation of linear momentum gives                 \[{{m}_{1}}{{u}_{1}}+{{m}_{2}}{{u}_{2}}={{m}_{1}}{{v}_{1}}+{{m}_{2}}{{v}_{2}}\] \[\Rightarrow \]                           \[{{m}_{2}}{{v}_{2}}=\frac{3u}{2}\]                              ? (ii) Conservation of kinetic energy gives \[\frac{1}{2}{{m}_{1}}u_{1}^{2}+\frac{1}{2}{{m}_{2}}u_{2}^{2}=\frac{1}{2}{{m}_{1}}v_{1}^{2}+\frac{1}{2}{{m}_{2}}v_{2}^{2}\] \[\Rightarrow \]               \[{{m}_{2}}v_{2}^{2}=\frac{15{{u}^{2}}}{8}\]                                       ? (ii) Hence, on solving Eqs. (i) and (ii), we get                                 \[{{m}_{2}}=1.2kg\]


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