Physics - Determine Pith Ball Charges

[babelii]

Homework Statement

Two pith balls equally charged and each with mass of 1.5g. While one ball is suspended by a thread, the other is brought close to it and a state of equilibrium is reached. In that situation, the two balls are separated by 2.6cm and the thread is attached to the suspended ball makes an angle of 20deg with the vertical. Calculate the charge on each of the pith balls.

m = 1.5*10^-3kg
d = 0.026m

Homework Equations

F = (kQ1Q2)/(r²)

The Attempt at a Solution

I tried finding the force by the work done formula since we have an angle we could include, but i do not get any further than that.

 

[Delphi51]

I don't think you can get it that way because you have no means of calculating the work done by the hand pushing the stationary ball.
Use forces. Begin with a diagram of the three forces on the suspended ball when equilibrium is reached. Then write that the sum of the vertical forces is zero and the sum of the horizontal forces is zero (because F=ma and there is no acceleration).