Two identical small spheres of mass 2 g are fastened to the ends of an insulating thread of length 0.6m. The spheres are suspended by a hook in the ceiling from the centre of the thread. The spheres are given identical electric charges and hang in static equilibrium with an angle of 30 degrees between the string halves. Calculate the magnitude of the charge on each sphere. So both the spheres are experiencing the gravitational force, electric force and tension force. And each side to wich each charge is hung is 0.3m. I am guessing we have to use trig since the angle is given. Also since both the spheres are given the same charges, there will be repulsion. We could use F=Kq1q2/r^2. (how do we find r)This is all I can get from this problem. Could someone help me with this?