Four charges, each of charge +e, are at the four corners of a square of side a = 1 cm. The four charges are fixed in place and are considered to be of point-size. Gravity plays no role in this question.
[Figure: Square with side length a showing charges +e at each corner]
(a) Sketch a diagram of the electric field due to this charge system.
(b) What is the net force acting upon one of the charges?
(c) What is the electrostatic potential energy of this charge system?
(d) Now suppose that two of the charges are protons and the other two are positrons. A positron is the electron's anti-particle. It has the same mass as an electron but a charge of +e. The four charges are suddenly released. What are their speeds when they are a significant distance apart from one another?