3. Work and Energy on cube Identical positive point charges (+q) are arranged at 8 corners of a cube (edge length = a) as shown in the figure. For example, a point charge +q is at (6, 5, 5).\f(a) Calculate the electrostatic potential energy stored in the cube above. (b) Now bring another point charge (+q) from infinity to the origin (the center of a cube) while all the charges at the corners remain fixed in space. How much work by an external agent is needed to bring the point charge to the origin from infinity? (c) We still have 8 point charges (+q) fixed at the corners in a cube. Suppose an electron (mass m, charge -e) is released from rest at the point (x, y, =) = (0, 0, ;). Describe its subsequent motion. At what other point in its subsequent motion, if any, will the electron be at rest? What is the electron's speed if it passes through the origin? Hint: Consider the principle of energy conservation