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Homework Help: I have one question regarding Kinetic Energy

  1. Mar 26, 2015 #1
    • HW Template missing as it was moved from another forum
    The question is.
    There are two particles, one with charge -q and the other with charge Q, and -q particle rotates around the Q particle at a radius r1. What is the Energy at this point?
    The answer is like this: E= KE + U
    So now I know that U= -kQq/r1
    But according to the answer: KE= kQq/2r1. And I have no idea how they found this KE. Your help would be appreciated. Thanks in advance.
  2. jcsd
  3. Mar 26, 2015 #2
    If one charge is revolving around another, then there is a centripetal force acting on the revolving charge. Can you relate this to the attractive force between the charges? How does this relate to the kinetic energy of the revolving charge?
  4. Mar 26, 2015 #3
    Thnx. I got it. Now I'm laughing how I couldn't figure it out .
  5. Mar 26, 2015 #4
    Happens to the best of us :)
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