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!

Electrostatic equilibrium, deflection of a cobweb

  1. Dec 10, 2014 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    After creating a FBD and analyzing the forces, I get the equation for the angle as

    ## tan \theta = \frac{k q^2}{m g r^2} ##

    3. The attempt at a solution

    I have tried to find a way to find the distance between the charges ## r ##, but the only way I can think of to find it required the angle. I do not know how the question can be solved without knowing at least one of the two variables, and my first inclination is just to assume there is not enough information.

    Any help would be appreciated! Thanks!
  2. jcsd
  3. Dec 10, 2014 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I think you can write another equation for r in terms of theta using the geometry alone..

    Hint: You are given the dimension 0.35m
  4. Dec 10, 2014 #3

    Doc Al

    User Avatar

    Staff: Mentor

    Find the relationship between r and ##\theta##.

    (CWatters beat me to it while I was snoozing!)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted