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!

Electric Forces; Coloumb's Law question

  1. Dec 10, 2006 #1
    1. The problem statement, all variables and given/known data
    three spheres, each with a negative charge of 4.0 X 10^-6 C, are at the vertices of an equilateral triangle whose sides are 0.20m long. Calculate the magnitude and direction of the net electric force on each sphere.


    2. Relevant equations

    Fe= kq1q2/r^2, where k is the constant, k=9.0 X 10^9 N*m^2/C^2

    3. The attempt at a solution

    i plugged in the values..but I don't seem to be getting the answer. There are 2 forces acting on each of the spheres, right? the answer is 6.2N
     
  2. jcsd
  3. Dec 10, 2006 #2

    OlderDan

    User Avatar
    Science Advisor
    Homework Helper

    Saying "I plugged in" is not telling us what you did. Yes there are two forces acting on each charge. How are they acting? How did you combine them?
     
  4. Dec 10, 2006 #3
    since Fe=kq1q2/r^2
    Fe= k*(4.0 X 10^-6C)^2/ (0.20m)^2
    Fe= 3.6N


    how are they acting? they are supposed to repel each other, but i don't understand how that would affect the magnitude of the force. To combine them, i think i have to add 3.6N + 3.6N..but that isn't working. What do you think?
     
  5. Dec 10, 2006 #4

    OlderDan

    User Avatar
    Science Advisor
    Homework Helper

    I think you need to remember that forces are vectors and need to be added as directional quantities. I did not check your numerical calculation, but I expect the vector addition is your problem.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?