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Homework Help: Kinetic Energy and Electric Potential

  1. Mar 13, 2010 #1
    1. The problem statement, all variables and given/known data

    Points A and B have electric potentials of 350 V and 160 V, respectively. When an electron released from rest at point A arrives at point C, its kinetic energy is KA.
    When the electron is released from rest at point B, however, its kinetic energy when it reaches point C is KB=2KA

    What is the electric potential at point C?
    What is the kinetic energy KA?


    2. Relevant equations

    KA=qV


    3. The attempt at a solution

    I found the solution to the first part by doing:

    2(VC-VA)=VC-VB
    2VC-700=VC-160
    VC=540

    For the second part, I did
    KA=qV
    KA=(1.6022*10^-19)*(540-350)
    KA=3.044*10^-17

    This isn't right. Any help would be awesome :)
     
  2. jcsd
  3. Mar 13, 2010 #2

    rl.bhat

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    Homework Helper

    Your answer is correct.
     
  4. Mar 14, 2010 #3
    Okay, well it says it wants the answer in something that looks like eV, is that the problem there?
     
  5. Mar 14, 2010 #4

    rl.bhat

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    Energy in eV = energy in Joules/charge on electron.
     
  6. Mar 14, 2010 #5
    So I would do 3.044*10^-17/1.60217646*10^-19?
    Which would be KA=190?
     
  7. Mar 14, 2010 #6
    190 is the correct answer. Thanks!
     
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