College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 10

A 1.00-g cork ball having a positive charge of 2.00 C is suspended vertically on a 0.500-m-long light string in the presence of a uniform downward-directed electric field of magnitude E = 1.00 × 10 5 N/C as in Figure P15.56. If the ball is displaced slightly from the vertical, it oscillates like a simple pendulum. (a) Determine the period of the ball's oscillation. (b) Should gravity be included in the calculation for part (a) Explain.