Two small metal cubes with masses 2.0 g and 4.0 g are tied together by a 5.0-cm-long massless string and are at rest on a frictionless surface. Each is charged to +2.0 μC.
a. What is the energy of this system?
b. What is the tension in the string?
c. The string is cut. What is the speed of each cube when they are far apart?