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Work and Energy with Electricity

  1. Jan 23, 2007 #1
    1. The problem statement, all variables and given/known data
    A 0.010-kg positively-charged particle is accelerated by a uniform electric field directed to the right. The object accelerates from 5.0 to 15.0 m/s while traveling a distance of 0.10 m.

    Use the definition of potential energy to determine the change in electric potential energy of the particle. Is the change an increase or a decrease?

    2. Relevant equations
    Wel = Kf - Ki
    Wel = -Delta-U
    Delta-V = W/q0

    3. The attempt at a solution
    The definition of electric potential is equal to -delta-U / q0
    Delta-U is negative because the work of the problem from Electric Field comes out to 1 Joule from the definition of work. So, delta-U is -1 J, meaning that the electric potential change is positive since q0 is positive - but I cannot figure out how to find q0's magnitude. I'm pretty sure I'm missing something from the given to determine the value of q0, but I'm otherwise stumped!
  2. jcsd
  3. Jan 23, 2007 #2
    you know the change in KE, use that to find the change in U and q
  4. Jan 23, 2007 #3
    How do they compare? I cannot find an equation in my textbook related U and q to the Change in Kinetic Energy.
  5. Jan 23, 2007 #4
    Law of Conservation of Energy, what its lost in potential it has gained in kinetic. U=qdeltaV
  6. Jan 23, 2007 #5
    Still though, I know U, but I don't know my q or delta-V values. Let me know if I'm overlooking something obvious that you're assuming that I know!
  7. Jan 24, 2007 #6
    You know the field and the distance it acts over
  8. Jan 24, 2007 #7
    Gotcha, it looks a lot better after a nights rest, I kept thinking it was Electric Potential, not Electric Potential Energy
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