The principle of the conservation of mechanical energy states that mechanical energy is constant as long as it is in an isolated system and subject only to conservative forces. Mechanical energy itself is the energy that is built up in an object due to the work done on it or due to the position of the object.
Mechanical energy can be either kinetic or potential energy. This type of energy is also sometimes defined as the ability to do work. This definition comes from the fact that any object that possesses energy, be it kinetic or potential, is able to do work.
Mechanical energy gives an object the ability to apply force to another object and cause the second object to be displaced from it's original place of origin. There is a formula to calculate the total mechanical energy of an object: the sum of the potential energy and the kinetic energy added together.
Potential energy has two forms, which are gravitational potential energy and elastic potential energy. Gravitational refers to the energy stored in an object due to its vertical position or height, while elastic refers to the energy stored in an object due to stretching or compressing the object. Either form of this potential energy is considered a type of mechanical energy.