Question

sphere A has a mass of 4.2*10^-2 kg and is tethered to a wall by a thin thread. Sphere a has an excess of 1.2 *10^12 electrons. Sphere B has a deficit of 3.5*10^12 electrons and is o.23 m from sphere A
a) determine the angle between the thread and the wall
b) determine the tension in the thread