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: Help with Energy at inelastic collision

  1. Jun 19, 2011 #1
    1. The problem statement, all variables and given/known data
    A particle of mass m1 and momentum p1 collides with a particle of mass m2 at rest. A reaction occurs, as a result giving two new particles, with masses m3 and m4, that are emitted at angles
    [itex]\theta_3[/itex] and [itex]\theta_4[/itex], in relation to the original direction of m1. Determine the energy Q that has been produced on the reaction in terms of the masses, the angles and p1.

    2. Relevant equations

    [tex]Q = T_f - T_i[/tex]
    [tex]T = \frac{p^2}{2 m}[/tex]

    3. The attempt at a solution

    [tex]p_1 = p_3 cos(\theta_3) + p_4 cos(\theta_4)[/tex]
    [tex]p_2 = 0 = p_3 sin(\theta_3) - p_4 sin(\theta_3)[/tex]
    [tex]Q = T_3 + T_4 - T_1[/tex]
    [tex]Q = \frac{{p_3}^2}{2m_3} + \frac{{p_4}^2}{2m_4} - \frac{{p_1}^2}{2m_1}[/tex]

    I'm stuck here.
    I suppose I have to, obviously, express both [itex]p_3[/itex] and [itex]p_4[/itex] in terms of [itex]p_1[/itex], but I'm not exactly sure of how to do it. Or maybe I just need some algebraic manipulation to get rid of both [itex]p_3[/itex] and [itex]p_4[/itex].

    Any help appreciated.
  2. jcsd
  3. Jun 19, 2011 #2


    User Avatar

    That absolutely correct, you need algebraic manipulation to express [itex]p_3[/itex] and [itex]p_4[/itex] in terms of [itex]p_1[/itex], [itex]\theta_3[/itex] and [itex]\theta_4[/itex].
  4. Jun 19, 2011 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    ... and these are the equations you need to manipulate:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook