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Homework Help: 2D momentum of two objects next to a wall

  1. Nov 24, 2009 #1
    1. The problem statement, all variables and given/known data
    We have two pucks next to a wall. Puck 1 has velocity v0=15 m/s in the direction y (as seen on the picture). Puck 2 is stationary. After the collision puck 1 moves in the opposite direction with velocity v1=10 m/s and puck 2 moves with unknown velocity in the direction x. The radius of puck 1 is r1=3cm and of puck 2 r2=6cm. The mass of puck 1 is m1=0.1kg and of puck 2 m2=0.5kg. The collision is not elastic.

    What is the velocity of puck 2 after the collision?

    http://img134.imageshack.us/img134/8082/breznaslova.jpg [Broken]

    2. Relevant equations
    Equation of momentum P=mv
    Pythagorean theorem c2=a2+b2

    3. The attempt at a solution
    First I calculated the angle using the radiuses of the pucks and I got Cos([tex]\alpha[/tex])=[tex]\frac{r2-r1}{r2+r1}[/tex]
    I got that [tex]\alpha[/tex] = 70.5 degrees.

    Then I went on to figure out momentums. I figured out this:
    http://img256.imageshack.us/img256/8120/breznaslova2.jpg [Broken]
    The angle between P0 and P2 is [tex]\alpha[/tex].
    Then I went on to make the P1 the hypotenus and the opposite is P1y which is the same as P=m1v1. From that I calculated the angle and then the adjacent P1x. Am I right to think that the velocity I am looking for is vx=[tex]\frac{P1x}{m2}[/tex].

    Thanks for any assistance.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 24, 2009 #2
    Does noone have an idea how to do this?
  4. Feb 5, 2010 #3
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