1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: What is the potential energy of this group of charges?

  1. Feb 15, 2016 #1
    1. The problem statement, all variables and given/known data
    Three electrons form an equilateral triangle 0.800 nm on each side. A proton is at the center of the triangle.

    2. Relevant equations
    U = k[(q_1*q_2)/r]

    3. The attempt at a solution
    I tried to use the following equation:

    k*[(3e^2)/(0.8*10^-9) - (3e^2)/(0.4*10^-9)]

    I plugged in 1.602*10^-19 for both e-values, and got the following answer:

    -6.4*10^-19 Volts

    However, it says that "I do not have the correct dimensions." I'm not sure what that error means or what I did wrong, so any help would be appreciated.
  2. jcsd
  3. Feb 15, 2016 #2


    User Avatar

    Staff: Mentor

    There's no question in your problem statement... thread titles don't really count as part of the problem statement. :smile:

    "Dimensions" refer to the units associated with your answer. What are the units of potential energy, as opposed to electric potential?
  4. Feb 15, 2016 #3
    Oh my goodness what a dumb mistake! thank you!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted