College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 32

Two small metallic spheres, each of mass m = 0.20 g, are suspended as pendulums by light strings from a common point as shown in Figure P15.15. The spheres are given the same electric charge, and it is found that they come to equilibrium when each string is at an angle of = 5.0° with the vertical. If each string has length L = 30.0 cm, what is the magnitude of the charge on each sphere