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Homework Help: Conservation of momentum

  1. May 6, 2014 #1
    1. The problem statement, all variables and given/known data
    A ball of mass m travels with speed v, hits a stationary ball with the same mass m and after collision they both move at speed v/2.
    From the point of view of the first ball the total momentum is -mv and after the collision it is 0. why isn't the law of conservation of momentum valid for this coordinate system?

    2. Relevant equations
    The first and second laws of newton, F=ma and that a body is at rest while no forces act on it are valid in all coordinate systems moving at constant speed.

    3. The attempt at a solution
    The coordinate system has acceleration during the collision so F=ma isn't valid. i don't know to continue from here and i guess it's the right answer, no?
  2. jcsd
  3. May 6, 2014 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Sounds good to me. The coordinate system attached to the first ball is not an inertial reference frame.
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