College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 25

Two hard rubber spheres, each of mass m = 15.0 g, are rubbed with fur on a dry day and are then suspended with two insulating strings of length L = 5.00 cm whose support points are a distance d = 3.00 cm from each other as shown in Figure P15.59. During the rubbing process, one sphere receives exactly twice the charge of the other. They are observed to hang at equilibrium, each at an angle of = 10.0° with the vertical. Find the amount of charge on each sphere.