A uniformly charged thin ring has radius 10.0 cm and total charge +12.0μC . An electron is placed on the ring's axis a distance 25.0 cm from the centre of the ring and is constrained to stay on the axis of the ring. The electron is then released from rest.
(a) describe the subsequent motion of the electron.
(b) find the speed of the electron when it reaches the centre of the ring.