Horsepower (HP) is the name of several units of measurement A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention and/or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of measurement of power The dimension of power is energy divided by time. The SI unit of power is the watt , which is equal to one joule per second. Non-SI units of power include ergs per second (erg/s), horsepower (hp), metric horsepower (Pferdestärke (PS) or cheval vapeur, CV), and foot-pounds per minute. One horsepower is equivalent to 33,000 foot-pounds per minute,. The most common definitions equal between 735.5 and 750 watts The watt is a derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit measures the rate of energy conversion. It is defined as one joule per second [1].
Horsepower was originally defined to compare the output of steam engines A steam engine is a heat engine that performs mechanical work using steam as its working fluid with the power of draft horses A draft horse , draught horse (UK) or dray horse (from the Anglo-Saxon dragan meaning to draw or haul; compare Dutch dragen meaning to carry), less often called a heavy horse, is a large horse bred for hard, heavy tasks such as ploughing and farm labour. There are a number of different breeds, with varying characteristics but all share common. The unit was widely adopted to measure the output of piston engines, turbines, electric motors, and other machinery. The definition of the unit varied between geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on January 1, 2010, the use of horsepower in the EU is only permitted as supplementary unit.
The definition of the horsepower also has varied between different applications:
- The mechanical horsepower also known as imperial horsepower of exactly 550 foot-pounds per second is approximately equivalent to 745.7 watts The watt is a derived unit of power in the International System of Units , named after the 18th-century Scottish engineer James Watt. Its unit symbol is W. The unit measures the rate of energy conversion.
- The metric horsepower of 75 kgf A kilogram-force , or kilopond (kp), is a unit of force equal to the magnitude of the force exerted on one kilogram of mass by a 9.80665 m/s2 gravitational field (standard gravity, a conventional value approximating the average magnitude of gravity on Earth).[citation needed] Therefore one kilogram-force is by definition equal to 9.80665 newtons-m per second is approximately equivalent to 735.499 watts.
- The boiler horsepower is used for rating steam boilers A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications and is equivalent to 34.5 pounds (≈15.65 kilograms) of water evaporated per hour at 212 degrees Fahrenheit Fahrenheit is the temperature scale proposed in 1724 by, and named after, the physicist Daniel Gabriel Fahrenheit . Today, the temperature scale has been replaced by the Celsius scale in most countries. It is still in use in few nations, such as United States and Belize (=100 degrees Celsius Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale two years before his death. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature interval (a difference between two temperatures, =373.15 Kelvin The kelvin is a unit increment of temperature and is one of the seven SI base units. The Kelvin scale is a thermodynamic (absolute) temperature scale referenced to absolute zero, the absence of all thermal energy. So by definition, the temperature of a substance at absolute zero is zero kelvin (0 K). The secondary reference point on the Kelvin), or 9,809.5 watts.
- One horsepower for rating electric motors An electric motor uses electrical energy to produce mechanical energy, very typically through the interaction of magnetic fields and current-carrying conductors. The reverse process, producing electrical energy from mechanical energy, is accomplished by a generator or dynamo. Many types of electric motors can be run as generators, and vice versa is equal to 746 watts.
- The Pferdestärke PS (German translation of horsepower) is a name for a group of similar power measurements used in Germany around the end of the 19th century, all of about one metric horsepower in size.[2][3]
- The Royal Automobile Club It has two club houses, one in London at 89-91 Pall Mall, and the other in the countryside at Woodcote Park, Surrey, next to the City of London Freemen's School. Like most other "gentlemen's clubs" in London today, the Royal Automobile Club now has women as well as men as members (RAC) horsepower or British tax horsepower The tax horsepower or taxable horsepower was an early system by which taxation rates for automobiles were reckoned in some European countries like Britain, Belgium, Germany, France, and Italy; some US states like Illinois charged license plate purchase and renewal fees for passenger automobiles based on taxable horsepower. The tax horsepower is an estimate based on several engine dimensions.
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History of the unit
The development of the steam engine provided a reason to compare the output of horses The horse is a hooved (ungulate) mammal, a subspecies of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today. Humans began to domesticate horses around 4000 BCE, and their domestication is believed to have been widespread by 3000 BCE. Although with that of the engines that could replace them. In 1702, Thomas Savery Thomas Savery was an English inventor, born at Shilstone, a manor house near Modbury, Devon, England wrote in The Miner's Friend: "So that an engine which will raise as much water as two horses, working together at one time in such a work, can do, and for which there must be constantly kept ten or twelve horses for doing the same. Then I say, such an engine may be made large enough to do the work required in employing eight, ten, fifteen, or twenty horses to be constantly maintained and kept for doing such a work…" The idea was later used by James Watt James Watt, FRS, FRSE was a Scottish inventor and mechanical engineer whose improvements to the Newcomen steam engine were fundamental to the changes brought by the Industrial Revolution in both the Kingdom of Great Britain and the world to help market his improved steam engine A steam engine is a heat engine that performs mechanical work using steam as its working fluid. He had previously agreed to take royalties of one third of the savings in coal from the older Newcomen steam engines The atmospheric engine invented by Thomas Newcomen in 1712, today referred to as a Newcomen steam engine , was the first practical device to harness the power of steam to produce mechanical work. Newcomen engines were used throughout Britain and Europe, principally to pump water out of mines, starting in the early 18th century. James Watt's later.[4] This royalty scheme did not work with customers who did not have existing steam engines but used horses instead. Watt determined that a horse could turn a mill wheel 144 times in an hour (or 2.4 times a minute). The wheel was 12 feet in radius, therefore the horse travelled 2.4 × 2π × 12 feet in one minute. Watt judged that the horse could pull with a force In physics, a force is any influence that causes a free body to undergo an acceleration. Force can also be described by intuitive concepts such as a push or pull that can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform. A force has both magnitude and direction, making it a of 180 pounds. So:
This was rounded to an even 33,000 ft·lbf/min.[5]
Others[who?] recount that Watt determined that a pony could lift an average 220 lbf (0.98 kN) 100 ft (30 m) per minute over a four-hour working shift. Watt then judged a horse was 50% more powerful than a pony and thus arrived at the 33,000 ft·lbf/min figure.[citation needed]
Engineering in History recounts that John Smeaton John Smeaton, FRS, was an English civil engineer – the first self-proclaimed civil engineer, and often regarded as the "father of civil engineering" – responsible for the design of bridges, canals, harbours and lighthouses. He was also a capable mechanical engineer and an eminent physicist. He was associated with the Lunar Society initially estimated that a horse could produce 22,916 foot-pounds per minute. John Desaguliers increased that to 27,500 foot-pounds per minute. "Watt found by experiment in 1782 that a 'brewery horse' was able to produce 32,400 foot-pounds per minute." James Watt and Matthew Boulton standardized that figure at 33,000 the next year.[6]
Most observers familiar with horses and their capabilities estimate that Watt was either a bit optimistic or intended to underpromise and overdeliver; few horses can maintain that effort for long. Regardless, comparison with a horse proved to be an enduring marketing tool.[citation needed]
A healthy human can produce about 1.2 hp briefly (see orders of magnitude This page lists examples of the power in watts produced by various different sources of energy. They are grouped by orders of magnitude, and each section covers three orders of magnitude, or a factor of one thousand) and sustain about 0.1 hp indefinitely; trained athletes can manage up to about 2.5 hp briefly[7] and 0.3 hp for a period of several hours.
Horsepower from a horse
R. D. Stevenson and R. J. Wassersug published an article in Nature 364, 195-195 (15 July 1993) calculating the upper limit to an animal's power output. The peak power over a few seconds has been measured to be as high as 14.9 hp. However, Stevenson and Wassersug observe that for sustained activity, a work rate of about 1 hp per horse is consistent with agricultural advice from both 19th and 20th century sources.
Current definitions
The following definitions have been widely used:
In certain situations it is necessary to distinguish between the various definitions of horsepower and thus a suffix is added: hp(I) for mechanical (or imperial) horsepower, hp(M) for metric horsepower, hp(S) for boiler (or steam) horsepower and hp(E) for electrical horsepower.
Hydraulic horsepower is equivalent to mechanical horsepower. The formula given above is for conversion to mechanical horsepower from the factors acting on a hydraulic system.
Mechanical horsepower
Assuming the third CGPM The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures . It is one of the three organizations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention) of 1875. It meets in Sèvres (in the southwestern suburbs of Paris) (1901, CR 70) definition of standard gravity Standard gravity, usually denoted by g0 or gn, is the nominal acceleration due to gravity at the Earth's surface at sea level, defined to be precisely 9.80665 m/s2 . This value was established by the 3rd CGPM (1901, CR 70), gn=9.80665 m/s2, is used to define the pound-force as well as the kilogram force, and the international avoirdupois pound The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement. A number of different definitions have been used, the most common today being the international avoirdupois pound of exactly 0.45359237 kilograms (1959), one mechanical horsepower is:
Or given that 1 hp = 550 ft·lbf/s, 1 ft = 0.3048 m, 1 lbf ≈ 4.448 N, 1 J = 1 N·m, 1 W = 1 J/s: 1 hp = 746 W
Thu, 24 Jun 2010 17:05:20 GMT+00:00
Chicago Sun-Times Ford has done a lot to improve its pony car in recent years and the new 305- horsepower V-6 and 412- horsepower V-8 engines for 2011 are both great. ...
Kleo
Wed, 01 Sep 2010 20:57:24 GM
When Aston Martin then revealed that said car wouldn't even receive a single . horsepower. increase over the paltry 99 . horsepower. found in the 2012 iQ, the world shared a collective sigh of disappointment. Then Aston Martin told the world ...
