Mechanical Energy Summary
From Thermal-FluidsPedia
Mechanical energy is the total energy an object has excluding the thermal and internal energies associated with the structure of its atoms and molecules. In other words, it is the sum of its potential, kinetic, and rotational energies. Mechanical energy is what it takes to lift, move, turn, and twist an object. Examples of mechanical energy are energy possessed by a fast ball, energy stored in a spring or a rubber band, and the energy it takes to move a heavy object up a stairs. Simple machines are devices that are at our disposal to carry out the difficult tasks with less effort; they allow us to do the same amount of work by applying a smaller force (effort) but over longer distances. In performing any task there are always some frictional forces that we must overcome. For this reason, some mechanical energy is always converted to heat. In other words, in real systems, mechanical efficiencies are always smaller than “one”.
References
(1) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005