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.