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Antother Collision

  1. Nov 23, 2005 #1
    Antother Collision!!!!!!!!!

    A billiard ball moving with a speed of [tex]v = 2.2m/s[/tex] strikes an identical stationary ball a glancing blow. After the collision, one ball is found to be moving at a speed of [tex]v_2 = 1.1m/s[/tex] in a direction making a [tex] \theta = 60^o[/tex] angle with the original line of motion. Find the velocity of the other ball?

    I dont really know where to start...Maybe conserving momentum?
  2. jcsd
  3. Nov 23, 2005 #2
    Would I just do this:

    [tex]1/2m_1v_1_i^2 +1/2m_2v_2_i^2 = 2(1/2m_1v_1_f^2) + 1/2m_2v_2_f^2[/tex]

    since all of the masses are the same they cancel out and since the second ball is stationary..it is 0

    [tex]v_1_i^2 = 2v_1_f^2 + 2v_2_f^2[/tex]
    [tex]1/2(2.2)^2 = 2sin \theta(1.1)^2 + 2v_2_f^2[/tex]
    [tex]v_2_f = 1.53m/s[/tex]
  4. Nov 23, 2005 #3


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    Staff: Mentor

    Why is the kinetic energy term of m1 doubled on the right hand side?

    In an elastic collision, kinetic energy and momentum are conserved. Momentum is conserved in the x and y directions.
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