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Homework Help: Electric field problem with acceleration

  1. Apr 5, 2010 #1
    An electron moving through an electric
    field experiences an acceleration of 7200 ×
    10^3 m/s2.
    Find the magnitude of the electric force
    acting on the electron. The Coulomb constant
    is 8.99 × 109 N · m2/C2 and the fundamental
    charge is 1.60 × 10−19

    So I thought that since E*q=F then it would also be the same as F=m*a so it would be:
    (E)*(1.60e-19 C)=(9.11e-31kg)(7200e3 m/s^2)
    which when you do out the calculations would get you E=4.0995e-5.
    Somehow I think Newton is crying in the grave with this witchcraft I just created.
    Did I have the right idea or am I way off?
  2. jcsd
  3. Apr 5, 2010 #2
    looks good to me
  4. Apr 5, 2010 #3
    I haven't thought through this method myself; but I assume that from what the question gives you the approach should be slightly different. I think this because I don't see the reason for giving you the Coulomb constant, unless it is a Red-Herring and I fell for it=]
    I'm not sure tbh, Electric fields are not my strong point.
  5. Apr 5, 2010 #4
    I tried it and it was wrong. So I guess that I did something wrong. Any ideas?
  6. Apr 5, 2010 #5


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    Homework Helper
    Gold Member

    According to the problem statement, it's asking for the electric force, not the electric field strength. So I guess you only really need F = ma.
  7. Apr 5, 2010 #6
    Moral of the story: I need to learn to read. Thank you so much!
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