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Homework Help: Inelastic Collision

  1. Mar 17, 2010 #1
    1. The problem statement, all variables and given/known data
    Given the figure below and knowing that the coefficient of restitution is e=0.8 find the final velocities of the spheres.

    2. Relevant equations
    m1v1 + m2v2 = m1v1' + m2v2'
    e = v2' - v1'/v1 - v2

    3. The attempt at a solution
    I have tried this a bunch of different ways and am not getting the answer (va' = 18.2 ft/s, vb' = 6.57 ft/s).

    I tried breaking the velocity of ball a up into components along the center axis and the axis perpendicular.

    Va on the center axis = 18cos(40) = 13.79 ft/s

    I then set up equations along the axis for conservation of momentum and COR:

    (2/32.2)*13.79 + (3/32.2)*(-12) = (2/32.2)*Va' + (3/32.2)*Vb'

    so Vb' = -2.807 - .667*Va'


    e = (Vb' - Va')/(13.79 - (-12)) = 0.8 , after plugging in Vb' from above

    I get Va' = -70.39 ft/s which is way off.

    I have tried other methods also that are also wrong, some closer though.

    I am just completely stuck now.

    Attached Files:

  2. jcsd
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