Calculating Electric Force: Neutral Sphere A & Charged Sphere B

[Cory]

How do I calculate Electric forces when objects are dangling from insulated wire. For example
Neutral metal sphere A, of mass 0.10kg hangs from an insulating wire 2.0m long. An identical metal sphere B, with charge -q, is brough into contact with the sphere A. The spheres repel and stelle down as shown in the following figure

.\ <) = 12
...\
...\
...\
(B)...(A)
* <) AB(top) = 90 degrees.
Calculate the initial charge on B.

 

[ponjavic]

I don't remember these formulas if you could give me some formulas for electric forces I'd help you out!

 

[Cory]

Sorry, I posted this in the wrong section, it is now in the right section with the formula.