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Homework Help: Electric Potential

  1. Feb 7, 2010 #1
    1. The problem statement, all variables and given/known data

    A 2mm diameter plastic bead is charged to -1nC (*note - the bead is not hollow)

    a) An alpha particle is fired at the bead from far away with a speed of 1x106 m/s and it collides head-on. What is the impact speed?

    b) An electron is fired at the bead from far away. It "reflects", with a turning point .1mm from the surface of the bead. What was the electrons initial speed?

    2. Relevant equations

    V=PEe/q V=kq/r W=k q1 q2 (1/ri-1/rf) F=ma E=F/q E=k[q]/r2

    I don't know which of these equations are even needed, but I thought I would include as many relevant ones I could think of.

    3. The attempt at a solution

    I don't even know where to start with this. The only thing I can think of would be to maybe do something with conservation of energy? but I am given no distances for anything so I'm not sure how to make that or any of the above equations work.
  2. jcsd
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