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: Perfectly elastic collision

  1. Dec 2, 2008 #1
    1. The problem statement, all variables and given/known data
    In an isolated system, cart1 (with mass = 1 kg and vi1 = 2) has a perfectly elastic collision with cart2 (with mass = 2 kg and vi2 = 0). Find the velocity of cart1 and the velocity of cart2 after the collision.

    2. Relevant equations
    1/2m1vi12 + 1/2m2vi22 = 1/2m1v1f2 + 1/2m2v2f2

    m1vi1 + m2v2i = m1v1f + m2v2f

    3. The attempt at a solution

    I plugged in all of the numbers.

    For momentum I got
    2= V1f + 2 V2f

    For kinetic energy I got
    4 = V1f2 + 2V2f2

    Next I solved for V1f and plugged it into the equation.

    I just need some confirmation that my answer is right.

    It doesn't seem correct.

    I got:
    V2f = 2
    V1f = -2
  2. jcsd
  3. Dec 2, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You could check your answers yourself. Do they satisfy both the kinetic energy and momentum equations?
  4. Dec 2, 2008 #3
    No, they don't. You're right that was an easy way to check myself.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook