JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति JEE PYQ - One Dimensional Motion

  • question_answer
    A goods train accelerating uniformly on a straight railway track, approaches an electric pole standing on the side of track. Its engine passes the pole with velocity u and the guard's room passes with velocity v. The middle wagon of the train passes the pole with a velocity. [JEE ONLINE 19-05-2012]

    A) \[\frac{u+v}{2}\]

    B) \[\frac{1}{2}\sqrt{{{u}^{2}}+{{v}^{2}}}\]

    C) \[\sqrt{uv}\]

    D) \[\sqrt{\left( \frac{{{u}^{2}}+{{v}^{2}}}{2} \right)}\]

    Correct Answer: D

    Solution :

    [d] Let ‘S’ be the distance between two ends ‘a’ be the constant acceleration
    As we know \[{{V}^{2}}-{{u}_{2}}=2aS\]or\[aS=\frac{{{V}^{2}}-{{u}^{2}}}{2}\]
    Let V be velocity at mid point.
    Therefore, \[V_{c}^{2}-{{u}^{2}}=2a\frac{S}{2}\]
    \[V_{c}^{2}={{u}^{2}}+aS\]
    \[V_{c}^{2}={{u}^{2}}+\frac{{{V}^{2}}-{{u}^{2}}}{2}\]
    \[{{V}_{c}}=\sqrt{\frac{{{u}^{2}}+{{v}^{2}}}{2}}\]


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