DUMET Medical DUMET Medical Solved Paper-2002

  • question_answer
    An object A of mass 2 kg is moving with a velocity of 3 m/s and collides head-on with an object B of mass 1 kg moving in opposite direction with a velocity of 4 m/s. After collision both objects coalesce, so that they move with a common velocity equal to :

    A)  3 m/s         

    B)  2 m/s

    C)  1 m/s         

    D)  \[\frac{2}{3}\,m/s\]

    Correct Answer: D

    Solution :

    Key Idea: This is a case of inelastic collision. When two bodies stick together on colliding then only momentum is conserved (inelastic collision). Hence, momentum before collision = momentum after collision \[{{m}_{1}}\,{{v}_{1}}+{{m}_{2}}\,{{v}_{2}}=({{m}_{1}}+{{m}_{2}})v\] Given, \[{{m}_{1}}=2\,kg,\,{{v}_{1}}=3\,m/s,\,{{m}_{2}}=1\,kg\], \[{{v}_{2}}=-4\,m/s\] \[v=\frac{2\times 3-1\times 4}{2+1}=\frac{2}{3}\,m/s\].


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