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: The Linear Momentum of a System of Particles

  1. Apr 5, 2006 #1
    Hello All, I have a question that i cant seem to get.

    If someone could help me get started on part a that would be great.

    So far i have tryed using P =m1v1 and cant seem to find any other equations that would help with the problem.

    Any help is great!
    Thank You

    A cart with mass 390 g moving on a frictionless linear air track at an initial speed of 1.2 m/s undergoes an elastic collision with an initially stationary cart of unknown mass. After the collision, the first cart continues in its original direction at 0.57 m/s.

    (a) What is the mass of the second cart?
    (b) What is its speed after impact?
    (c) What is the speed of the two-cart center of mass?
  2. jcsd
  3. Apr 5, 2006 #2
    Elastic means kinetic energy is conserved. You have two conservation equations:
    [tex] m_1 v_{1i}= m_1v_{1f} + m_2v_{2f}[/tex] and
    [tex] m_1 v_{1i}^2 = m_1 v_{1f}^2 + m_2v_{2f}^2[/tex]
    You can use these to determine the unknowns.
  4. Apr 5, 2006 #3


    User Avatar
    Staff Emeritus
    Science Advisor

  5. Apr 5, 2006 #4
    but how would i solve out for m2 or v2 when the equation has both in it?

    Does v2f = v1i - v1f ?

    Edit: I got it now thanks a lot !
    Last edited: Apr 5, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook