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Homework Help: Electric field and speed - find acceleration.

  1. Feb 4, 2009 #1
    1. The problem statement, all variables and given/known data
    A proton accelerates from rest in a uniform electric field of 640N/C. At some later time, its speed is 1.20x10^6m/s.
    a) Find the magnitude of the acceleration of the proton.
    b) How long does it take the proton to reach this speed?
    c) How far has it moved in that interval?
    d) What is its kinetic energy at the later time?

    2. Relevant equations

    3. The attempt at a solution
    I think I can figure this problem out after knowing how to get started. I was confused as to how to start without having the mass. Any help?
  2. jcsd
  3. Feb 4, 2009 #2


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    Homework Helper

    You can look up the mass and charge of a proton.
    Use F = ma.
    Of course it is the electric field that causes the force, so put in the formula for that.
  4. Feb 4, 2009 #3
    Thank you. I went outside for a break and had the revelation. I feel stupid now. I got the answer for each part now. I don't know why I wasn't thinking about looking up the charge and mass. Thanks again!
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