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Homework Help: Two objects colliding & sticking together, what is their final speed?

  1. Dec 7, 2008 #1
    1. The problem statement, all variables and given/known data

    Two freight cars, each with a mass of 2.5 multiplied by 10^5 kg, collide and stick together.
    One was initially moving at 3.4 m/s and the other was at rest. What is their final speed?


    2. Relevant equations
    m(vf-vi)


    3. The attempt at a solution
    (2.5*10^5)(0-3.4)= -850,000
    = -8.5 * 10^5 m/s
     
  2. jcsd
  3. Dec 7, 2008 #2
    The main thing you can use in the problem is conservation of momentum:

    m1v1+m2v2=(m1+m2)v'

    This equality is a result of the completely inelastic collision. The question asks you to solve for v'.
     
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