Mechanical energy is the sum of the kinetic and potential energy of an object that gives it the ability to do work. Work is defined as the ability to cause an object to be displaced by another object due to force.
Kinetic energy is the energy of motion, and potential energy is the energy of position. An example of potential energy is a baseball that is about to be thrown from the top of a building. Once the baseball is thrown, it has kinetic energy since it is now in motion. When the baseball lands on a surface such as the roof of a car, causing an indent, it demonstrates mechanical energy as the ability to do work and cause displacement.