Question: A square plane 0.25 m on a side carries a charge of 10-4 C distributed uniformly over the plane. A small fragment of mass 0.15g and charge 4 x 10-8 C breaks off the surface and is repelled by the plane.
Part A: If the fragment starts from rest, how fast is it going 5 cm from the plane?
I need help to solve the above question and hint: approximate the plane as infinite.