1. Not finding help here? Sign up for a free 30min 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!

8-point charges on a vertice of a cube

  1. Sep 20, 2011 #1
    1. The problem statement, all variables and given/known data

    I attached a picture to make it easier...

    2. Relevant equations

    Coulomb's Law: F=k(q1*q2)/(r)^2

    a^2+b^2=c^2

    Charge properties

    3. The attempt at a solution

    I uploaded a picture of one of the cleaner sheets of work I used so far...Basically, I suppose I'm at a loss at figuring out where to start, and where to finish. I thought I was on the right track by calculating the magnitude of each charge affecting the vertex A, but apparently it hasn't got me very far.
     

    Attached Files:

  2. jcsd
  3. Sep 20, 2011 #2

    PeterO

    User Avatar
    Homework Helper

    I would start by calculating the force between two adjacent charge - for example the one directly below A. All the other forces and components will be fractions of that - the size of the fraction determined by the different distances involved. [and angles when looking at components].
    That will keep the arithmetic simple and you may be able to keep track of the forces.
     
  4. Sep 20, 2011 #3
    Okay, I understand finding the force between the two adjacent ones. No problem. And I get that the other components are fractions of them, but how would I go about calculating them simply?
     
  5. Sep 20, 2011 #4

    PeterO

    User Avatar
    Homework Helper

    For "diagonal" charges, the separation is up by a factor of sqrt(2), so the force is down by a factor of 2 courtesy of the inverse square law [there is a factor of R2 in the denominator of the formula.
    The body diagonal distance is up by a factor of sqrt(3)
     
  6. Sep 20, 2011 #5
    You guys on this forum are the best! Thank you!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook