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In thermodynamics, motive power is an agency, as water or steam, used to impart motion. Generally, motive power is defined as a natural agent, as water, steam, wind, electricity, etc., used to impart motion to machinery; a motor; a mover. The term may also define something, as a locomotive or a motor, which provides motive power to a system. In current use, motive power may be thought of as a synonym for either "work", i.e. force times distance, or "power", an effect producing motion, dependending on the context of the discussion. ‹ The template below has been proposed for deletion. ...
Impact of a drop of water. ...
In physical chemistry, and in engineering, steam refers to vaporized water. ...
Motion involves change in position, such as this perspective of rapidly leaving Yongsan Station In physics, motion means a change in the position of a body relative to a reference point, as measured by a particular observer in a particular frame of reference. ...
Lightning strikes during a night-time thunderstorm. ...
A machine is any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of tasks. ...
A motor is a device that converts energy into mechanical power, and is often synonymous with engine. ...
A locomotive (from Latin loco motivus) is a railway vehicle that provides the motive power for a train, and has no payload capacity of its own; its sole purpose is to move the train along the tracks. ...
Work (abbreviated W) is the energy transferred in applying force over a distance. ...
In physics, power (symbol: P) is the amount of work done per unit of time. ...
History In 1679 physicist Denis Papin conceived the idea of using steam to power a piston and cylinder engine, by watching a steam release valve of a bone-digester rhythmically move up and down. In 1698, based on Papin’s designs, mechanical designer Thomas Savery build the first engine. The first scientific treatise on the energetics of engines was the 1824 paper: Reflections on the Motive Power of Fire written by French physicist Sadi Carnot. Denis Papin Denis Papin (August 22, 1647 - c. ...
A steam engine is an external combustion heat engine that makes use of the thermal energy that exists in steam, converting it to mechanical work. ...
Thomas Savery (c. ...
Sadi Carnot Nicolas Léonard Sadi Carnot (June 1, 1796 - August 24, 1832) was a French mathematician and engineer who gave the first successful theoretical account of heat engines, the Carnot cycle, and laid the foundations of the second law of thermodynamics. ...
As an example, the Newcomen engine of 1711 was able to replace a team of 500 horses that had “powered” a wheel to pump water out of out a mine, i.e. to “move” buckets of water vertically out of mine. Hence, we have precursory model to the term motive power. Based on this model, in 1832, Carnot defined work as “weight lifted through a height”, being the very same definition used to this day. Diagram of the Newcomen steam engine Thomas Newcomens atmospheric engine, today referred to as a Newcomen steam engine, was the first practical device to harness the power of steam to produce mechanical work. ...
1824 definition Carnot states, in the footnotes to his famous 1824 publication, “We use here the expression motive power to express the useful effect that a motor is capable of producing. This effect can always be likened to the elevation of a weight to a certain height. It has, as we know, as a measure, the product of the weight multiplied by the height to which it is raised.”
In this manner, Carnot is actually referring to "motive power" in the same manner we currently define "work". If we were to include a unit of time in Carnot's definition, we would then have the modern-day definition for power: Work (abbreviated W) is defined as the line integral of a scalar product of force and displacement vectors (see below). ...
Thus Carnot's definition of motive power is not consistent with the modern physics definition of "power", nor the modern usage of the term.
1834 definition In 1834, the French mining engineer Emile Clapeyron refers to Carnot’s motive power as “mechanical action”. As an example, during the expansion stroke of a piston engine he states that: “the gas will have developed a quantity of mechanical action during its expansion given by the integral of the product of the pressure times the differential of the volume.” Clapeyron then goes on to use graphical methods to show how this "mechanical action", i.e. work in modern terms, could be calculated. Emile_Clapeyron Benoit Paul Émile Clapeyron (February 26, 1799 - January 28, 1864) was an French engineer and physicist, considered as one of the founders of thermodynamics. ...
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