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Homework Help: Kinetic energy

  1. Oct 31, 2006 #1
    Determine from classical mechanics (using a head-on collision with recoil at 180 degrees) what fraction of an electron’s kinetic energy can be transferred to a mercury atom in an elastic collision. Derive an approximate value of the fraction.

    well ok let the mass of the electron be m_e
    initial velocity of electron v_1
    fina lvelocity v_2
    mercury atom mass m_Hg
    mercury atom fina lvelocity v_Hg

    [tex] \frac{1}{2} m_{e} v_{1}^2 = \frac{1}{2} m_{Hg} v_{Hg}^2 + \frac{1}{2} m_{e} v_{2}^2 [/tex]

    the fraction of kinetic energy is Kf/Ki right

    [tex] \frac{K_{f}}{K_{i}} = \frac{v_{2}^2}{v_{1}^2} [/tex]

    do i use momentum concepts to find v2 in terms of v1

    still it doesnt give me a numerical value... if thats what the question is asking...
  2. jcsd
  3. Oct 31, 2006 #2
    bump :D
    for help :)
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