Two small plastic balls each carrying a charge of magnitude q and a mass of 10 g hang from strings of negligible mass. The balls are attracted to each other, and the strings to which they are attached make 20° angles with the vertical, as shown. The balls are separated by a distance of d = 2.0 cm. Find (a) the magnitude of the electric force acting on each ball, (b) the tension in each string, and (c) q, the magnitude of the charge on each ball.