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Homework Help: Why can't we use cons of energy in this problem? (conceptual)

  1. Feb 19, 2012 #1
    Two pucks collide on a frictionless air-hockey table. Initally, puck A is traveling at 3.5 mls and puck B is at rest. After the collision, puck A moves away at a speed of 2.5 m/s and an angle of 30.0 from the initial direction. Find the final velocity of puck B. Puck A has a mass of 3.0 kg and puck B has a mass of 5.0 kg.

    I know how to do the problem, but we can't we apply the conservation of energy methods because it is an elastic collision?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 19, 2012 #2


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    In inelastic collisions you can't use conservation of energy.
  4. Feb 19, 2012 #3
    He says that it is an elastic collision.
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