Electric field 2

How fast will an electron hit a charged sphere?

An electron accelerates from a distance of 20cm from the surface to the surface of a 10cm radius metal sphere charged with 5 nC. Given that potential a distance r from the centre of a sphere of charge, Q is given by the equation V = kQ/r calculate the speed of the electron as it hits the surface of the sphere.

k = 9 x 109 VmC-1

e = -1.6 x 10-19 C

me = 9.1 x 10-31 kg