Mechanical energy is defined as the energy of an object or system due to its motion or position. It is the sum of the kinetic and potential energy of an object. All moving objects have mechanical energy, whether they are in motion or at a position relative to zero potential energy. For example, a moving truck has mechanical energy because of its motion (i.e. kinetic energy).
Objects that possess mechanical energy are capable of doing work. Machines and human bodies use mechanical energy to do work and perform motions. An object’s mechanical energy enables it to apply force to another object to displace the other object. An example is the wrecking ball of a demolition machine. It applies force to a building structure in order to demolish the building. The wall of the structure becomes displaced once the wrecking ball hits it. The wrecking ball possesses potential energy when held at a height and kinetic energy when it falls.
There are two forms of mechanical energy. Kinetic energy is the energy of an object due to its motion, while potential energy is stored mechanical energy due to its height above the ground or because it is squeezed, bent or stretched. Mechanical energy exists in every system in the universe. It is found everywhere, from a leaf falling to the ground to a hammer driving a nail. Mechanical energy turns, throws, twists, pushes and pulls.