 #1
gsquare567
 15
 0
Homework Statement
A charged cork ball of mass 1g is suspended on a light string in the presence of a uniform electric field. When E = (3i + 5j) * 10^5 N/C, the ball is in equilibrium at [tex]\theta[/tex] = 37 degrees. Find the charge on the ball and the tension on the string.
====================
\
[tex]\theta[/tex]\
 \
 \ / < uniform electric field, E = (3i + 5j) * 10^5 N/C
 \/
 O < charged cork ball, mass = 1g, q = ?
i
^


> j
Homework Equations
F(electric) = qE
F(grav) = mg(j)
The Attempt at a Solution
I tried using the cosine law with the forces to isolate for [tex]\theta[/tex]
a^2 = b^2 + c^2 2bc * cos([tex]\alpha[/tex])
but it canceled out.
Anyways,
[tex]\alpha[/tex] = [tex]\theta[/tex]
a = F(elec)
b = F(grav)
c = F(res) = F(elec) + F(grav)
Any ideas? Thanks!