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!

Finding the E-field of a mass hanging from a string

  1. Jul 7, 2011 #1
    9. [1pt]
    prob04_ball_in_field.gif

    As shown in the figure above, a ball of mass 0.480 g and positive charge q =32.7microC is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of theta=15.0o from the vertical. What is the magnitude of the electric field?

    Fx= Fe - Tsin(theta)= 0
    Fy= Tcos(theta) = 0

    Tsin(theta)/Tcos(theta) = Fe\mg

    Than E= Fe/q

    So Tan(theta)mg = Fe/q = E

    I got (Tan(15)*.480*9.8)/32.7e-6= 3.9 e 4
    Where did I go wrong?
     
  2. jcsd
  3. Jul 7, 2011 #2

    gneill

    User Avatar

    Staff: Mentor

    Note the units in which the mass was specified.

    EDIT: Note also that since this is a homework problem, it should have been posted in one of the homework forums, in particular the Introductory Physics Forum.

    EDIT by mentor: this thread has been moved to the appropriate location.
     
    Last edited by a moderator: Jul 8, 2011
  4. Jul 7, 2011 #3
    Its right! Thank you for responding so fast!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Finding the E-field of a mass hanging from a string
Loading...