1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Elastic collision in two dimensions

  1. Dec 3, 2007 #1
    1. The problem statement, all variables and given/known data

    On a frictionless surface, a 0.35 kg puck moves horizontally to the right (at an angle of 0°) and a speed of 2.3 m/s. It collides with a 0.23 kg puck that is stationary. After the collision, the puck that was initially moving has a speed of 2.0 m/s and is moving at an angle of −32°. What is the velocity of the other puck after the collision?

    2. Relevant equations
    Momentum before= momentum after
    kinetic energy before= kinetic energy after
    AB=AB cos (x)

    3. The attempt at a solution

    From Momentum before= momentum after, I got
    M1=first mass
    Vi1=initial velocity of the first mass
    Vf1=final velocity of the first mass...and I think you get the rest

    From the kinetic energy before= kinetic energy after, i got

    Now i'm kinda lost on what to do...some advice?
    Last edited: Dec 3, 2007
  2. jcsd
  3. Dec 3, 2007 #2
    ok so you have one puck moving straight to the right initially. this has a certain momentum. this certain momentum is equal to the momentum of both of the pucks after the collision (which you already stated)

    initial momentum = .35 x 2.3 = .805 to the right (0 degrees)

    if you know that one will move at -32 degrees with a velocity of 2 so determine its momentum. all you have to do now is find the other momentum vector that, when added to this one, will equal .805 at 0 degrees.
    Last edited: Dec 3, 2007
  4. Dec 3, 2007 #3
    i got it, thanks
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Elastic collision in two dimensions