1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: What are the velocities of the balls after the collision?

  1. Mar 11, 2014 #1
    1. The problem statement, all variables and given/known data

    A 0.50 kg ball with a speed of 1.5 m/s in the positive direction has a head-on elastic collision with a stationary 0.80 kg ball. What are the velocities of the balls after the collision?

    2. Relevant equations

    I've used the Ek = (1/2)m(v^2) so far.

    3. The attempt at a solution

    I used the Ek formula above to find that the kinetic energy of the ball that was initially moving (0.50 kg at 1.5 m/s). It was 0.5625 J, and because it's an elastic collision, all of that Ek is conserved and the combined Ek of both moving balls post-collision should be 0.5625. I'm just unsure of how to find out which ball has which velocity now (the actual hard part of the question, lol). I've used substitution but I keep getting 0=0, lol! Can anyone help me out?
  2. jcsd
  3. Mar 12, 2014 #2


    User Avatar
    Homework Helper

    what substitution have you used? remember, it's total momentum that's conserved.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted