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Homework Help: Electrostatic potential and velocity

  1. May 21, 2010 #1
    1. The problem statement, all variables and given/known data

    Point A is at an electrostatic potential of +1V relative to point B in a vacuum. An electron initially at rest at B moves to A. What is its velocity in m/s?

    2. Relevant equations

    E = PE + KE
    PE= J/q * q
    KE = 0.5 mv^2 (where v = velocity)

    3. The attempt at a solution
    Based on the definiton of an electron volt (eV), the energy of the electron is 1eV or 1.6E-19 Joules.

    In solving the first equation:
    1.6E-19 J = 1 J/C * e- + 0.5mv^2
    e-= 1.6E-19C
    based on my error (whatever that may be)
    0 = 0.5mv^2 which means v=0, this doesn't seem correct.

    Any suggestions?
     
  2. jcsd
  3. May 21, 2010 #2

    Char. Limit

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    Gold Member

    Re: Velocity

    Shouldn't the charge of the electron be negative? Then you'd end up with

    [tex]2x=.5mv^2[/tex]

    Where x is the 1.6*10^-19...
     
  4. May 21, 2010 #3
    Re: Velocity

    Thanks,

    I knew it was something simple that I had missed.
     
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