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 questions

  1. Apr 6, 2008 #1
    i was absent for a couple days and i have absolutely no idea whats going on. Help with any of the questions would be amazing.


    for #1 first i found the diagonal distance equals [tex]\sqrt{98}[/tex]
    then i used the formula F=KC x q1 x q2/ [tex]r^{2}[/tex] to find the electric force between the 8nC charge and the two others:
    8.99E9(8E-6 x 7E-6)/ 98 = 5.14E-3
    and 8.99E9(8E-6 x 2E-6)/ 98 = 1.47E-3

    after that i had no clue, except i know #4 is 0
    Last edited: Apr 7, 2008
  2. jcsd
  3. Apr 7, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF.

    Don't forget to include the direction when calculating the force. The formula you gave is actually a vector equation, and to get the magnitude and direction right you should add the two forces as vectors.
    Also, when writing down a final answer, include units (if they ask you to calculate force, your answer will be something like: F = ... N in the x-direction, or [itex]\vec F[N] = \cdots \hat{x}[/itex]).

    You have learned to work with vectors already, is that correct?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Electric forces questions
  1. Electric Force Question (Replies: 14)

  2. Electric force question (Replies: 10)