JEE Main & Advanced Sample Paper JEE Main Sample Paper-26

  • question_answer
    A mass m moves with a velocity v and collides in elastically with another identical mass. After v collision the 1 st mass moves with velocity \[\frac{v}{\sqrt{3}}\] in a direction perpendicular to the initial direction of motion. Find the speed of the second mass after collision.

    A)  v                                

    B)  \[\sqrt{3v}\]

    C)  \[\frac{2}{\sqrt{3}}v\]                          

    D)  \[\frac{v}{\sqrt{3}}\]

    Correct Answer: C

    Solution :

    In x-direction \[m{{u}_{1}}+0=0+m{{v}_{x}}\]Or \[mv=m{{v}_{x}}\]\[{{v}_{x}}=v\] In y-direction \[0+0\,=m\left( \frac{v}{\sqrt{3}} \right)\,-m{{v}_{y}},\,\,or\,\,{{v}_{y}}=\frac{v}{\sqrt{3}}\] Velocity of second mass after collision, \[v'=\,\sqrt{{{\left( \frac{v}{\sqrt{3}} \right)}^{2}}+{{v}^{2}}}\,=\sqrt{\frac{4}{3}{{v}^{2}}}\]\[v'\,=\frac{2}{\sqrt{3}}v\]

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