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Homework Help: Electron collide

  1. Nov 27, 2007 #1
    electron together

    2 electrons are fired at speed v towards one another. Knowing that each electron has a charge of e an mass m, what is the minimum distance that the two electrons will reach after fired at one another?

    My book has a different answer than me so I have to check with you guys.

    I wrote, -dE = dEk

    -(E2 - E1) = (Ek2 - Ek1) - Ek2 is zero to for minimizing radius, and we assume E1 to be zero.

    E2 = Ek1

    2ke^2/r =mv^2

    2ke^2 / mv^2 = r

    Now in our book, they had this question with numbers, i derived this formula and plugged in my values and it didn't match the answer in the book.
    Last edited: Nov 27, 2007
  2. jcsd
  3. Nov 27, 2007 #2
    i never get any answers here man :(
  4. Nov 28, 2007 #3
    no luck?
  5. Nov 28, 2007 #4


    User Avatar
    Staff Emeritus
    Science Advisor

    It seems that the electric potential energy is correct, but using conservation of energy, that would have to equal the combined initial kinetic energies of the two electrons, which would be 2 * 1/2 mv2 = mv2.
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