P. 3920. A large vertical insulating sheet is charged uniformly. The surface charge density is . A small neutral body of mass m is suspended on a long insulating thread of length l next to the sheet. Then the small body is given a charge of q, and left alone.
a) Find the greatest angle between the thread and the vertical.
b) Find the greatest speed of the small body.
c) Find the period of the motion. Data: l=1 m, m=10-3 kg, q=10-8 C, =10-6 C/m2.