1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

    User Avatar
    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

    User Avatar
    Homework Helper

    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!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook