motive power

Motive power is a term in thermodynamics referring to the harnessed energy or force that is used to power a mechanical device or system. Most simply, it's any source of power that imparts motion. Motive power is expressed mathematically as force X distance.

Motive power, as a concept, can be described as that which provides power to a system. The term motive power is most often used in science and engineering industries. Water, steam and wind are a few of the natural agents that provide motive power. Examples for water as a motive power include waterwheels, devices used to harvest tidal power and rain-powered solar panels. Steam pressure is used to move machinery and store power through pressure vessels and piston systems such as in locomotive engines. Wind turbines generate electricity and are a well-known example of motive power.

The use of power to power a mechanical system can be dated back to 1711 with the Newcomen engine, which moved buckets of water out of a well vertically. This engine created enough power to replace a team of 500 horses that had been used to pump water out of a mine. The Newcomen engine contributed significantly to the invention of the steam engine during the 18^th century. The word motive derives from this movement, and lead to the standardized expression of engine motive power as horsepower as a comparison to the power of draft horses.