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Homework Help: What am I doing wrong? Potential Difference

  1. Feb 17, 2008 #1
    1. The problem statement, all variables and given/known data
    On attachment. Part B only. I got C.

    2. Relevant equations
    mass of proton is 1.673*10^-27
    q0 = 1.60*10^-19

    3. The attempt at a solution

    For part B I thought I could divide the intial speed by 2 and plug it back into the energy conservation equation:

    .5mv^2 + q0V1 = .5mv^2 + q0V2 and solve for (V1 - V2) which would be the potential difference but it doesn't seem to work.

    Attached Files:

  2. jcsd
  3. Feb 18, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    That should work just fine. (Show what you actually did.)

    Another way to look at it is: By what fraction must the total energy be decreased to bring the speed to half its initial value? Compare that with the answer you got for part A.
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