A seat belt is a vehicle safety device designed to secure the occupant of a vehicle against harmful movement that may result during a collision or a sudden stop. A seat belt functions to reduce the likelihood of death or serious injury in a traffic collision by reducing the force of secondary impacts with interior strike hazards, by keeping occupants positioned for maximum effectiveness of the airbag and by preventing occupants being ejected from the vehicle in a crash or if the vehicle rolls over; when in motion, the driver and passengers are travelling at the same speed as the car. If the driver makes the car stop or crashes it, the driver and passengers continue at the same speed the car was going before it stopped. A seatbelt applies an opposing force to the driver and passengers to prevent them from falling out or making contact with the interior of the car. Seatbelts are considered Primary Restraint Systems, because of their vital role in occupant safety. An analysis conducted in the United States in 1984 compared a variety of seat belt types alone and in combination with air bags.
The range of fatality reduction for front seat passengers was broad, from 20% to 55%, as was the range of major injury, from 25% to 60%. More the Centers for Disease Control and Prevention has summarized this data by stating "seat belts reduce serious crash-related injuries and deaths by about half." Most seatbelt malfunctions are a result of there being too much slack in the seatbelt at the time of the accident. In 1946, Dr. C. Hunter Shelden opened a neurological practice at Huntington Memorial Hospital in Pasadena, California. In the early 1950s, Dr. Shelden made a major contribution to the automotive industry with his idea of retractable seat belts; this came about his from his care of the high number of head injuries coming through the emergency room. He investigated the early seat belts whose primitive designs were implicated in these injuries and deaths. To reduce the high level of injuries he was seeing, he proposed, in late 1955, retractable seat belts, recessed steering wheels, reinforced roofs, roll bars, automatic door locks, passive restraints such as the air bag.
Subsequently, in 1966, Congress passed the National Traffic and Motor Vehicle Safety Act requiring all automobiles to comply with certain safety standards. American car manufacturers Nash and Ford offered seat belts as options, while Swedish Saab first introduced seat belts as standard in 1958. After the Saab GT 750 was introduced at the New York Motor Show in 1958 with safety belts fitted as standard, the practice became commonplace. Glenn Sheren, of Mason, submitted a patent application on March 31, 1955 for an automotive seat belt and was awarded US Patent 2,855,215 in 1958; this was a continuation of an earlier patent application that Mr. Sheren had filed on September 22, 1952. However, the first modern three point seat belt used in most consumer vehicles today was patented in 1955 U. S. Patent 2,710,649 by the Americans Roger W. Griswold and Hugh DeHaven; the Swedish national electric utility, did a study of all fatal, on-the-job accidents among their employees. The study revealed that the majority of fatalities occurred while the employees were on the road on company business.
In response, two Vattenfall safety engineers, Bengt Odelgard and Per-Olof Weman, started to develop a seat belt. Their work was presented to Swedish manufacturer Volvo in the late 1950s, set the standard for seat belts in Swedish cars; the three-point seatbelt was developed to its modern form by Swedish inventor Nils Bohlin for Volvo—who introduced it in 1959 as standard equipment. In addition to designing an effective three-point belt, Bohlin demonstrated its effectiveness in a study of 28,000 accidents in Sweden. Unbelted occupants sustained fatal injuries throughout the whole speed scale, whereas none of the belted occupants were fatally injured at accident speeds below 60 mph. No belted occupant was fatally injured. Bohlin was granted U. S. Patent 3,043,625 for the device; the world's first seat belt law was put in place in 1970, in the state of Victoria, making the wearing of a seat belt compulsory for drivers and front-seat passengers. This legislation was enacted after trialing Hemco seatbelts, designed by Desmond Hemphill, in the front seats of police vehicles, lowering the incidence of officer injury and death.
A 2-point belt attaches at its two endpoints. A simple strap was first used March 12, 1910 by pilot Benjamin Foulois, a pioneering aviator with the Aeronautical Division, U. S. Signal Corps, so he might remain at the controls during turbulence. A lap belt is a strap; this was the most installed type of belt prior to legislation requiring three-point belts, is found in older cars. Coaches are equipped with lap belts. University of Minnesota Professor James J. Ryan was the inventor of and held the patent on the automatic retractable lap safety belt. Ralph Nader cited Ryan's work in Unsafe at Any Speed and in 1966 President Lyndon Johnson signed two bills requiring safety belts in all passenger vehicles starting in 1968; until the 1980s, three-point belts were available only in the front outboard seats of cars. Evidence of the potential of lap belts to cause separation of the lumbar vertebrae and the sometimes associated paralysis, or "seat belt syndrome", led to progressive revision of passenger safety regulations in nearly all developed countries to require three-point belts first in all outboard seating position
A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used. Although some mopeds, such as the VéloSoleX, had friction drive to the front tire, a motorcycle engine drives the rear wheel, power being sent to the driven wheel by belt, chain or shaft; some 2,000 units of the Megola were produced between 1921-1925 with front wheel drive, the modern Rokon, an all terrain motorcycle with both wheels driven, has been produced since 1960. Most engines have a gearbox with up to six ratios. Reverse gear is found on heavy tourers, for example the Honda GL1600, sidecar motorcycles, such as the Ural; the rider changes gears on most motorcycles using a foot-pedal and manual clutch, but early models had hand-levers. More some have automatic or semi-automatic gearboxes. Outside the United States, engine capacities ranged from about 50 cc to 650 cc. In the United States, V-twin engined-motorcycles with capacities of 850 cc or more have been the norm since the 1920s.
The first motorcycles were powered by steam engines. The earliest example is the French Michaux-Perreaux steam velocipede of 1868; this was followed by the American Roper steam velocipede of 1869, a number of other steam powered two and three wheelers and sold to the public on through the early 20th century. Using frames based both on the earlier boneshaker and the later—and in many ways modern—safety bicycle design, these early steam motorcycles experimented with a variety of engine placement strategies, as well as transmission and options. While today nearly every motorcycle has its engine in the center of the frame; the origins of the scooter engine arrangement can be traced back to the 19th century but the current layout became adopted after the Great War. The modern equivalent remains much the same today; the Otto cycle gasoline internal combustion engine was first used on an experimental two-wheeler created by Gottlieb Daimler to test the practicality of such an engine in a vehicle. This motorcycle, the Daimler Reitwagen, is credited as the world's first motorcycle by many authorities on the assumption that a motorcycle is defined not as any two-wheel motor vehicle, but a two-wheel internal combustion engine motor vehicle.
The Oxford English Dictionary, for example, defines the word motorcycle this way. The steam cycles were simply neglected and forgotten by many historians as the Michaux-Perreaux waited forty years on display in the National Motor Museum, Beaulieu. In recent years, a surge in interest in clean energy has put many new electric powered two wheelers on the market, they are registered as motorcycles or scooters, without the type of powerplant being an issue. Diesel motorcycles were experimented with in the 20th century, are again the subject of interest due to fuel economy and the needs of military logistics; the USMC has ordered a new diesel motorcycle, the M1030 M1, that can use the same fuel, JP-8, as the rest of their armored vehicles, aircraft and trucks. The overwhelming majority of the motorcycles produced and used in the world today have small displacement air-cooled single-cylinder engines, both two- and four-strokes. In the wealthier parts of the world and Japan, larger displacements and multiple cylinders are common alongside small-displacement bikes required by various licensing and rider experience requirements, so a diverse range of sizes, cylinder numbers and cooling systems are seen on the road.
Many developed countries have graduated licensing, where a rider is licensed for a period of time to ride only smaller-displacement motorcycles before being allowed to ride larger ones. In the United States, there are no such mandates, so the mix is skewed further to the largest displacements, consumer demand drives manufacturers to offer their largest motorcycles to that country, to export far fewer sub-600 cc models to the American market. All production motorcycles have gasoline internal combustion engines. Both four-stroke and two-stroke engines are used, but strict emission laws have led to far fewer two-strokes. A few have used Wankel rotary engines, but no Wankel bikes are in production. Motorcycle engines can be air cooled or liquid cooled, optionally include oil cooling as well; some scooters use an electric motor. The 2009 TT races introduced a new category'TTX' for electric bikes using batteries. Motorcycle engines can be mounted transversely. Motorcycles with transversely mounted engines are more suited to have belt final-drive.
Motorcycles with longitudinally mounted. Motor scooters have the engine as part of the rear suspension, so the engine is not fixed rigidly to the main frame. Instead, the combined engine-transmission-swingarm assembly is pivoted to follow the road surface and is part of the "unsprung weight"; the chain final-drive of scooters runs in an oil-bath within the engine casings. "Step-through" motorcycles may have a scooter-type arrangement. Two-stroke engines have fewer moving parts than four-stroke engines
A manual transmission known as a manual gearbox, a standard transmission or colloquially in some countries as a stick shift, is a type of transmission used in motor vehicle applications. It uses a driver-operated clutch engaged and disengaged by a foot pedal or hand lever, for regulating torque transfer from the engine to the transmission. A conventional 5-speed manual transmission is the standard equipment in a base-model vehicle, while more expensive manual vehicles are equipped with a 6-speed transmission instead; the number of forward gear ratios is expressed for automatic transmissions as well. Manual transmissions feature a driver-operated clutch and a movable gear stick. Most automobile manual transmissions allow the driver to select any forward gear ratio at any time, but some, such as those mounted on motorcycles and some types of racing cars, only allow the driver to select the next-higher or next-lower gear; this type of transmission is sometimes called a sequential manual transmission.
In a manual transmission, the flywheel is attached to the engine's crankshaft and spins along with it. The clutch disc is in between the pressure plate and the flywheel, is held against the flywheel under pressure from the pressure plate; when the engine is running and the clutch is engaged, the flywheel spins the clutch plate and hence the transmission. As the clutch pedal is depressed, the throw out bearing is activated, which causes the pressure plate to stop applying pressure to the clutch disk; this makes the clutch plate stop receiving power from the engine, so that the gear can be shifted without damaging the transmission. When the clutch pedal is released, the throw out bearing is deactivated, the clutch disk is again held against the flywheel, allowing it to start receiving power from the engine. Manual transmissions are characterized by gear ratios that are selectable by locking selected gear pairs to the output shaft inside the transmission. Conversely, most automatic transmissions feature epicyclic gearing controlled by brake bands and/or clutch packs to select gear ratio.
Automatic transmissions that allow the driver to manually select the current gear are called manumatics. A manual-style transmission operated by computer is called an automated transmission rather than an automatic though no distinction between the two terms need be made. Contemporary automobile manual transmissions use four to six forward gear ratios and one reverse gear, although consumer automobile manual transmissions have been built with as few as two and as many as seven gears. Transmissions for heavy trucks and other heavy equipment have 8 to 25 gears so the transmission can offer both a wide range of gears and close gear ratios to keep the engine running in the power band. Operating aforementioned transmissions use the same pattern of shifter movement with a single or multiple switches to engage the next sequence of gear selection. French inventors Louis-Rene Panhard and Emile Levassor are credited with the development of the first modern manual transmission, they demonstrated their three-speed transmission in 1894 and the basic design is still the starting point for most contemporary manual transmissions.
This type of transmission offered multiple gear ratios and, in most cases, reverse. The gears were engaged by sliding them on their shafts, which required careful timing and throttle manipulation when shifting, so the gears would be spinning at the same speed when engaged; these transmissions are called sliding mesh transmissions or sometimes crash boxes, because of the difficulty in changing gears and the loud grinding sound that accompanied. Newer manual transmissions on 4+-wheeled vehicles have all gears mesh at all times and are referred to as constant-mesh transmissions, with "synchro-mesh" being a further refinement of the constant mesh principle. In both types, a particular gear combination can only be engaged when the two parts to engage are at the same speed. To shift to a higher gear, the transmission is put in neutral and the engine allowed to slow down until the transmission parts for the next gear are at a proper speed to engage; the vehicle slows while in neutral and that slows other transmission parts, so the time in neutral depends on the grade and other such factors.
To shift to a lower gear, the transmission is put in neutral and the throttle is used to speed up the engine and thus the relevant transmission parts, to match speeds for engaging the next lower gear. For both upshifts and downshifts, the clutch is released; some drivers use the clutch only for starting from a stop, shifts are done without the clutch. Other drivers will depress the clutch, shift to neutral engage the clutch momentarily to force transmission parts to match the engine speed depress the clutch again to shift to the next gear, a process called double clutching. Double clutching is easier to get smooth, as speeds that are close but not quite matched need to speed up or slow down only transmission parts, whereas with the clutch engaged to the engine, mismatched speeds are fighting the rotational inertia and power of the engine. Though automobile and light truck transmissions are now universally synchronized, transmissions for heavy trucks and machinery, motor
Boucherville is a city in the Montérégie region in Quebec, Canada. It is a suburb of Montreal on the South shore of the Saint Lawrence River. Boucherville is part of both the urban agglomeration of Longueuil and Montreal Metropolitan Community regional government. Boucherville was founded as a seigneurial parish in 1667 by Pierre Boucher, for whom the city was named. Pierre Boucher came from Mortagne-au-Perche, France. After having lived in Quebec City and Trois-Rivières, Boucher moved to the Percées Islands by the southern shores of Saint Lawrence River, where he founded Boucherville; the first Catholic church of the village of Boucherville was built in 1670. This church, made of wood, was replaced in 1712 by a building made of brick, it was replaced in 1801 by the current Sainte-Famille Church in 1801. Several families left Boucherville in the 18th century to found the communities of Sainte-Julie and Saint-Bruno-de-Montarville. In July 1843 fire destroyed much of the village. Sparks blowing from a steamer ignited a wooden building owned by Mr. Weilbrenner.
The fire spread and soon most of the village was on fire. In the end, the church, the chapel, two schools, 51 homes and pastures, 92 other buildings were destroyed; the village was progressively rebuilt. A new church was built on the site of the old one over the course of the following two years. Parts of the walls and front were reused. A stone school was built in 1851 at the intersection of Notre-Dame and Louis-Hippolyte-Lafontaine streets; the municipality of the parish Sainte-Famille de Boucherville was established in 1845. This large territory included the village of Boucherville. In 1856, Sainte-Famille de Boucherville was divided into two separate municipalities: the parish Sainte-Famille de Boucherville and the village of Boucherville. In 1854, seigneurial tenure was abolished. Pierre-Amable Boucher de Boucherville, last seigneur of Boucherville, died three years later; the village Boucherville was to become an important vacation resort by the end of the 19th century and early 20th century.
People from Montreal could access the village by ferry. Boucherville experienced significant growth after World War II; this expansion was confirmed by the construction of the Louis-Hippolyte Lafontaine Bridge-Tunnel. The parish Sainte-Famille de Boucherville ceded portions of its territory to Saint-Hubert in 1877, to Saint-Bruno-de-Montarville in 1950 and to the village of Boucherville in 1956; the village of Boucherville gained the status of city in 1957. In 1963, the city of Boucherville merged with the Sainte-Famille de Boucherville parish; this brought Boucherville to its current city limits. Boucherville opened a new'civic centre', including an indoor and outdoor pool, municipal offices and indoor arena in 1966; the centre was renamed in memory of the murdered cabinet minister Pierre Laporte. In August 2015, the Centre was closed as part of a three-year, $27 million refurbishment project; the shell of the old building will be blended into the new facility. Some of the equipment, such as the skating rink boards and glass will be reused in the Gilles-Chabot arena.
As part of the 2000–2006 municipal reorganization in Quebec, Boucherville ceased to exist as an independent city on January 1, 2002 and became a borough of Longueuil. However, after a 2004 referendum, it de-merged and was reconstituted as an independent city on January 1, 2006. However, it remains part of the urban agglomeration of Longueuil. Today, Boucherville is home to more than 40,000 a large industrial park. Founder Pierre Boucher is commemorated by a museum in his name at the Séminaire Saint-Joseph and a statue erected at the National Assembly of Quebec, in addition to a monument on the Boucherville's waterfront; the Harmonie neighbourhood is located between the boulevards de Mortagne, de Montarville, de Montbrun and de Normandie. Its development is recent and is residential with many upscale houses. Many park and green spaces decorate the neighbourhood; the multifunctional centre of Boucherville is there. The Quartier des villes et provinces de France neighbourhood is located between the streets de Normandie, Gay-Lussac, Ampère and boulevard Montarville.
All the streets and parks in this neighbourhood are named after provinces of France. The neighbourhood is composed of separate or semi-detached houses. Old Boucherville is the original section of the city that contains the former village and Sainte-Famille Church; the neighbourhood is located between Saint-Lawrence River, the boulevards du Fort Saint-Louis, de Montarville et de Montbrun. Many of the buildings there are classified as historic monuments; the industrial section of Boucherville covers the western part of the city. This section is divided into 3 industrial parks. Although these parks were inaugurated in the 1960s, it was during the last two decades that their expansion has been the greatest. In the early 1980s, they were little more 100 companies and 6 000 jobs scattered in the industrial section. Today, they are 15 000 jobs in various sectors. Additionally, the industrial section is home to 2 research centres; the Boisé du Tremblay Wildlife Reserve is located within this section. The Seigneurie is a residential neighbourhood.
It is located south of Fort Saint-Louis boulevard, north of de Mortagne boulevard, to the west of de Brouage street and east of the Industriel boulevard. The neighbourhood was built in the early 1960s; the Carrefour de la Seigneurie shopping mall acted as a commercial anchor to the area, hosting a Dominion supermarket, a branch of the Canadian Imperial Bank of Commerce, a convenience store, a pharmacy and a medical clinic. A Texaco gas station stood in its parking lot. All these businesses have since mo
Sequential manual transmission
A sequential manual transmission is a non-traditional type of manual transmission used on motorcycles and high-performance cars for auto racing, where gears are selected in order, direct access to specific gears is not possible. With traditional manual transmissions, the driver can move from gear to gear, by moving the gear lever to the appropriate position. A clutch must be disengaged before the new gear is selected, to disengage the running engine from the transmission, thus stopping all torque transfer; this type of transmission is referred to as a H-pattern because of the path that the shift lever takes as it selects the various gears. As the gear shifting process requires attention and dexterity that might be needed in managing sharp corners in car races, sequential transmission has been introduced into many competition rules as an alternative. A true sequential transmission will often use dog clutch engagement rather than the more usual synchromesh as fitted to a normal H-pattern road car gearbox.
Engagement using dogs requires only a brief interruption of engine torque to complete a shift into any adjacent gear. This allows shifting between gears without the use of the clutch; the clutch would be used only for standing starts. Sequential manual transmissions work by providing the driver with the ability to select the gear directly before or after the gear engaged; the shift lever is pulled back to select the adjacent higher gear and pushed forwards to select the adjacent lower gear. On a true sequential gearbox, the shift lever operates a ratchet mechanism that converts the fore & aft motion of the shift lever into a rotary motion; this rotary action turns a selector drum which has three or four tracks machined around its circumference. Running in the tracks are the selector forks, either directly, or via selector rods; these tracks deviate around the circumference and as the drum rotates, the selector forks running in the tracks are moved to select the required gear. Only a true sequential transmission has a shift mechanism.
Sequential gearboxes are used in nearly all modern motorcycles as it is too cumbersome to have a conventional H-pattern shifter and would take up too much space in the confines of a motorcycle frame. Having control over the gear shifter with the rider's left foot, frees their hands to operate both the clutch and brake without letting go of the handlebars. Sequential manual transmissions are true manual transmissions, should not be confused with automatic transmissions that provide some degree of user shifting input. One commercial example of this type of automatic transmission is the Tiptronic transmission. User shifting through buttons or lever does not mean that the transmission is a manual transmission. Beyond the ease of use from a driver's standpoint, an additional benefit of sequential manual gearboxes is that use of the clutch via foot pedal or hand control can be minimized or obviated, with the clutch used only for starting from a complete stop. Formula One cars of the 1990s made the most high-profile debut of this technology in motor sports, enhanced variations on this theme are still in use in many forms of road racing and drag racing today.
The simple push-pull action of the shift mechanism lends itself to semi-automatic control using either hydraulic or pneumatic actuators—a system referred to as paddle-shift. Instead of a manual gear lever, the driver is provided with a pair of flipper paddles on the steering wheel. Rally cars utilize just a double-acting single paddle: pulling on the right-hand paddle makes an up-shift and pulling on the left-hand paddle makes a down-shift; the paddle-shift system will use a sophisticated electronic control unit to provide the necessary logic to operate the shift mechanism. This type of paddle-shift system fitted to race and rally cars should not be confused with most of the current crop of paddle-shift systems fitted to some high-end road cars; these systems use a dual-clutch transmission or a conventional torque converter automatic transmission which allow driver input to select the gears. Although a sequential manual transmission can offer faster shift speeds and thus faster race times, many road-car-driving enthusiasts prefer a standard manual transmission, which—with a clutch pedal and the ability to skip gears—allows more driver input and a more traditional driving experience.
An article on sequential gearbox technology
In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels. For road vehicles with more than two axles, the wheelbase is the distance between the steering axle and the centerpoint of the driving axle group. In the case of a tri-axle truck, the wheelbase would be the distance between the steering axle and a point midway between the two rear axles; the wheelbase of a vehicle equals the distance between its rear wheels. At equilibrium, the total torque of the forces acting on a vehicle is zero. Therefore, the wheelbase is related to the force on each pair of tires by the following formula: F f = d r L m g F r = d f L m g where F f is the force on the front tires, F r is the force on the rear tires, L is the wheelbase, d r is the distance from the center of mass to the rear wheels, d f is the distance from the center of gravity to the front wheels, m is the mass of the vehicle, g is the gravity constant. So, for example, when a truck is loaded, its center of gravity shifts rearward and the force on the rear tires increases.
The vehicle will ride lower. The amount the vehicle sinks will depend on counter acting forces, like the size of the tires, tire pressure, the spring rate of the suspension. If the vehicle is accelerating or decelerating, extra torque is placed on the rear or front tire respectively; the equation relating the wheelbase, height above the ground of the CM, the force on each pair of tires becomes: F f = d r L m g − h c m L m a F r = d f L m g + h c m L m a where F f is the force on the front tires, F r is the force on the rear tires, d r is the distance from the CM to the rear wheels, d f is the distance from the CM to the front wheels, L is the wheelbase, m is the mass of the vehicle, g is the acceleration of gravity, h c m is the height of the CM above the ground, a is the acceleration. So, as is common experience, when the vehicle accelerates, the rear sinks and the front rises depending on the suspension; when braking the front noses down and the rear rises.:Because of the effect the wheelbase has on the weight distribution of the vehicle, wheelbase dimensions are crucial to the balance and steering.
For example, a car with a much greater weight load on the rear tends to understeer due to the lack of the load on the front tires and therefore the grip from them. This is why it is crucial, when towing a single-axle caravan, to distribute the caravan's weight so that down-thrust on the tow-hook is about 100 pounds force. A car may oversteer or "spin out" if there is too much force on the front tires and not enough on the rear tires; when turning there is lateral torque placed upon the tires which imparts a turning force that depends upon the length of the tire distances from the CM. Thus, in a car with a short wheelbase, the short lever arm from the CM to the rear wheel will result in a greater lateral force on the rear tire which means greater acceleration and less time for the driver to adjust and prevent a spin out or worse. Wheelbases provide the basis for one of the most common vehicle size class systems; some luxury vehicles are offered with long-wheelbase variants to increase the spaciousness and therefore the luxury of the vehicle.
This practice can be found on full-size cars like the Mercedes-Benz S-Class, but ultra-luxury vehicles such as the Rolls-Royce Phantom and large family cars like the Rover 75 came with'limousine' versions. Prime Minister of the United Kingdom Tony Blair was given a long-wheelbase version of the Rover 75 for official use, and some SUVs like the VW Tiguan and Jeep Wrangler come in LWB models In contrast, coupé varieties of some vehicles such as the Honda Accord are built on shorter wheelbases than the sedans they are derived from. The wheelbase on many commercially available bicycles and motorcycles is so short, relative to the height of their centers of mass, that they are able to perform stoppies and wheelies. In skateboarding the word'wheelbase' is used for the distance between the two inner pairs of mounting holes on the deck; this is different from the distance between the rotational centers
In physics, power is the rate of doing work or of transferring heat, i.e. the amount of energy transferred or converted per unit time. Having no direction, it is a scalar quantity. In the International System of Units, the unit of power is the joule per second, known as the watt in honour of James Watt, the eighteenth-century developer of the condenser steam engine. Another common and traditional measure is horsepower. Being the rate of work, the equation for power can be written: power = work time As a physical concept, power requires both a change in the physical system and a specified time in which the change occurs; this is distinct from the concept of work, only measured in terms of a net change in the state of the physical system. The same amount of work is done when carrying a load up a flight of stairs whether the person carrying it walks or runs, but more power is needed for running because the work is done in a shorter amount of time; the output power of an electric motor is the product of the torque that the motor generates and the angular velocity of its output shaft.
The power involved in moving a vehicle is the product of the traction force of the wheels and the velocity of the vehicle. The rate at which a light bulb converts electrical energy into light and heat is measured in watts—the higher the wattage, the more power, or equivalently the more electrical energy is used per unit time; the dimension of power is energy divided by time. The SI unit of power is the watt, equal to one joule per second. Other units of power include ergs per second, metric horsepower, foot-pounds per minute. One horsepower is equivalent to 33,000 foot-pounds per minute, or the power required to lift 550 pounds by one foot in one second, is equivalent to about 746 watts. Other units include a logarithmic measure relative to a reference of 1 milliwatt. Power, as a function of time, is the rate at which work is done, so can be expressed by this equation: P = d W d t where P is power, W is work, t is time; because work is a force F applied over a distance x, W = F ⋅ x for a constant force, power can be rewritten as: P = d W d t = d d t = F ⋅ d x d t = F ⋅ v In fact, this is valid for any force, as a consequence of applying the fundamental theorem of calculus.
As a simple example, burning one kilogram of coal releases much more energy than does detonating a kilogram of TNT, but because the TNT reaction releases energy much more it delivers far more power than the coal. If ΔW is the amount of work performed during a period of time of duration Δt, the average power Pavg over that period is given by the formula P a v g = Δ W Δ t, it is the average amount of energy converted per unit of time. The average power is simply called "power" when the context makes it clear; the instantaneous power is the limiting value of the average power as the time interval Δt approaches zero. P = lim Δ t → 0 P a v g = lim Δ t → 0 Δ W Δ t = d W d t. In the case of constant power P, the amount of work performed during a period of duration t is given by: W = P t. In the context of energy conversion, it is more customary to use the symbol E rather than W. Power in mechanical systems is the combination of forces and movement. In particular, power is the product of a force on an object and the object's velocity, or the product of a torque on a shaft and the shaft's angular velocity.
Mechanical power is described as the time derivative of work. In mechanics, the work done by a force F on an object that travels along a curve C is given by the line integral: W C = ∫ C F ⋅ v d t = ∫ C F ⋅ d x, where x defines the path C and v is the velocity along this path. If the force F is derivable from a potential applying the gradi