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Homework Help: Find the final velocity of the two pucks after the collision

  1. Oct 20, 2009 #1
    1. The problem statement, all variables and given/known data
    Two hockey pucks approach each other as shown in the figure below. Puck 1 has an initial speed of 21 m/s, and puck 2 has an initial speed of 14 m/s. They collide and stick together.

    2. Relevant equations

    3. The attempt at a solution The pucks didn't have a mass so I couldn't use the components.
  2. jcsd
  3. Oct 20, 2009 #2
    Almost always in a collision problem like this, when the mass is not given that means the m terms will cancel out. Either the two pucks are of equal mass and the m's easily cancel or the mass is different, but is a multiple of the other mass. For example, one mass might be m and the other 3m, but the m's still cancel. I don't know whether or not the masses are the same, but if it is not specified, I would assume they are of equal mass.
  4. Oct 20, 2009 #3


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    Gold Member

    You'll need to provide more information. This is an inelastic collision so the masses canceling out is unlikely except in only certain situations.
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