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Homework Help: Conservation of Motion Collision of two object

  1. Apr 22, 2010 #1
    1. The problem statement, all variables and given/known data
    A small car is moving at 1.3 m/s on an air track when it collides with a larger 3 kg cart at rest. After the collision, the small cart recoils at 0.850 m/s.
    What is the speed of the large cart after the collision?


    2. Relevant equations
    m1V1i + m2V2i = (m1+m2)V2f

    m1 = .2 kg
    m2 = 3 kg
    V1i = 1.3 m/s
    V2i = 0
    V1f = -.85 /ms
    V2f = ?

    3. The attempt at a solution

    .2*1.3 + 3*0= (.2+3) V2f
    .26 = 3.2 V2f
    V2f = .26/3.2
    V2f = .08125

    My answer came back wrong. Where am I making a mistake?
    Thanks
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 22, 2010 #2

    radou

    User Avatar
    Homework Helper

    If this is an elastic collision, then the carts don't move together after the collision.
     
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