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Homework Help: Electric Field problem

  1. Jan 11, 2005 #1
    A uniform electric field has a magnitude of 3.0x10^3 N/C. In a vacuum, a proton begins with a speed of 2.3x10^4 m/s and moves in the direction of this field. Find the speed of the proton after it has moved a distance of .003 m.

    I try to work out the problem with the equation F=qE to find the acceleration and plug that into a kinematics equation, but I do not have q. Can anyone help?
  2. jcsd
  3. Jan 11, 2005 #2


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    You are told it is a proton, so it has a charge equal in magnitude to an electron (with opposite sign). 1.6*10^-19 C, I think. You should look it up in your textbook.
  4. Jan 11, 2005 #3
    ah got it! I actually tried that just before I posted on here except I left the negative sign on the charge. Thanks alot!
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