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Units Of Length
A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. The most common units in modern use are the metric system, metric units, used in every country globally. In the United States the U.S. customary units are also in use. British Imperial units are still used for some purposes in the United Kingdom and some other countries. The metric system is sub-divided into International System of Units, SI and non-SI units. History Metric system SI The SI base unit, base unit in the International System of Units (SI) is the meter, defined as "the length of the path travelled by speed of light, light in vacuum during a time interval of seconds." It is approximately equal to . Other SI units are derived from the meter by adding Metric prefix, prefixes, as in millimeter or kilometer, thus producing systematic decimal multiples and submultiples of the base unit that span many orders of magnitude. For example, a kilometer is . Non ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measurement Unit
A unit of measurement, or unit of measure, is a definite magnitude (mathematics), magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement. For example, a length is a physical quantity. The metre (symbol m) is a unit of length that represents a definite predetermined length. For instance, when referencing "10 metres" (or 10 m), what is actually meant is 10 times the definite predetermined length called "metre". The definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to the present. A multitude of System of measurement, systems of units used to be very common. Now there is a global standard, the International System of Units (SI), the modern form of the metric system. In trade, weights and measures are often a su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X Unit
: ''For the software testing tools, see xUnit.'' The x unit (symbol xu) is a unit of length approximately equal to 0.1 pm (10−13 m). It is used to quote the wavelength of X-rays and gamma rays. Originally defined by the Swedish physicist Manne Siegbahn (1886–1978) in 1925, the x unit could not at that time be measured directly; the definition was instead made in terms of the spacing between planes of the calcite crystals used in the measuring apparatus. One x unit was set at of the spacing of the (200) planes of calcite at 18 °C. In modern usage, there are two separate x units, which are defined in terms of the wavelengths of the two most commonly used X-ray lines in X-ray crystallography: * the copper x unit (symbol xu(Cu Kα1)) is defined so that the wavelength of the Kα1 line of copper is exactly 1537.400 xu(Cu Kα1); * the molybdenum x unit (symbol xu(Mo Kα1)) is defined so that the wavelength of the Kα1 line of molybdenum Molybdenum is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chain (unit)
The chain (abbreviated ch) is a unit of length equal to 66 feet (22 yards), used in both the US customary and Imperial unit systems. It is subdivided into 100 links. (PDF) There are 10 chains in a furlong, and 80 chains in one statute mile. In metric terms, it is 20.1168 m long. By extension, chainage (running distance) is the distance along a curved or straight survey line from a fixed commencing point, as given by an odometer. The chain has been used since the early 17th century in England, and was brought by British settlers during the colonial period to other countries around the globe. In the United Kingdom, there were 80 chains to the mile, but until the early nineteenth century the Scottish and Irish customary miles were longer than the statute mile; consequently a Scots chain was about 74 (imperial) feet, an Irish chain 84 feet. These longer chains became obsolete following the adoption of the imperial system of units in 1824. In India, "metric chains" of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surveying
Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geometry), points and the Euclidean distance, distances and angles between them. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designated positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales. A professional in land surveying is called a land surveyor. Surveyors work with elements of geodesy, geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages, and the law. They use equipment, such as total stations, robotic total stations, theodolites, Satellite navigation, GNSS receivers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Determination Of The Rute And The Feet In Frankfurt
Determination is a positive emotional feeling that promotes persevering towards a difficult goal in spite of obstacles. Determination occurs prior to goal attainment and serves to motivate behavior that will help achieve one's goal. Empirical research suggests that people consider determination to be an emotion; in other words, determination is not just a cognitive state, but an affective state. In the psychology literature, researchers study determination under other terms, including challenge and anticipatory enthusiasm; this may explain one reason for the relative lack of research on determination compared to other positive emotions. In the field of psychology, emotion research focuses on negative emotions and the behaviors they prompt. However, positive psychology delves into determination as a positive emotion driving people toward action, leading to significant results like persistence and success. Etymology The word determination comes from the Latin word , meaning " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilot (aeronautics)
An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Some other aircrew members, such as navigators or flight engineers, are also considered aviators because they are involved in operating the aircraft's navigation and engine systems. Other aircrew members, such as drone operators, flight attendants, mechanics and ground crew, are not classified as aviators. In recognition of the pilots' qualifications and responsibilities, most militaries and many airlines worldwide award aviator badges to their pilots. Definition The first recorded use of the term ''aviator'' (''aviateur'' in French) was in 1887, as a variation of ''aviation'', from the Latin ''avis'' (meaning ''bird''), coined in 1863 by in ''Aviation Ou Navigation Aérienne'' ("Aviation or Air Navigation"). The term ''aviatrix'' (''aviatrice'' in French), now archaic, was formerly used for a female pilot. The term ''aviator'' (''aviateur'' i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Mile
A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees). Today the international nautical mile is defined as exactly . The derived unit of speed is the knot, one nautical mile per hour. Unit symbol There is no single internationally agreed symbol, with several symbols in use. * NM is used by the International Civil Aviation Organization. * nmi is used by the Institute of Electrical and Electronics Engineers and the United States Government Publishing Office. * M is used as the abbreviation for the nautical mile by the International Hydrographic Organization. * nm is a non-standard abbreviation used in many maritime applications and texts, including U.S. Government Coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fathom
A fathom is a unit of length in the imperial and the U.S. customary systems equal to , used especially for measuring the depth of water. The fathom is neither an international standard (SI) unit, nor an internationally accepted non-SI unit. Historically it was the maritime measure of depth in the English-speaking world but, apart from within the US, charts now use metres. There are two yards (6 feet) in an imperial fathom. Originally the span of a man's outstretched arms, the size of a fathom has varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Formerly, the term was used for any of several units of length varying around . Etymology The term (pronounced ) derives (via Middle English ''fathme'') from the Old English ''fæðm'', which is cognate with the Danish word ''favn'' and means "embracing arms" or "pair of outstretched arms". It is maybe also cognate with the Old High German wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailor
A sailor, seaman, mariner, or seafarer is a person who works aboard a watercraft as part of its crew, and may work in any one of a number of different fields that are related to the operation and maintenance of a ship. While the term ''sailor'' has its etymological roots from sailing, that is a time when sailing ships were the main mode of transport at sea, it now refers to the personnel of all watercraft regardless of the type of vessel, boat or ship. It encompasses people who operate ships professionally, be it for a military (navy) or civilian (merchant navy) or for Sailing (sport), sports or recreation. In a navy, there may be further distinctions: ''sailor'' may refer to any member of the navy even if they are based on land, while Seaman (rank), ''seaman'' may refer to a specific enlisted rank. Additionally, fisherman are seen as a distinct type of sailor, that is those engaged in fishing. Sailors have existed from the earliest periods in history as people as people used b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
League (unit)
A league is a unit of length. It was common in Europe and Latin America, but due to its highly inconsistent definition, it is no longer an official unit in any nation. Derived from an ancient Celtic unit and adopted by the Romans as the , the league became a common unit of measurement throughout western Europe. Since the Middle Ages, many values have been specified in several countries, ranging from 2.2 km (1.4 mi) to 7.9 km (4.9 mi). It may have originally represented, roughly, the distance a Preferred walking speed, person could walk in an hour. Definitions Ancient Rome The league was used in Ancient Rome, defined as 1½ mile#Roman, Roman miles (7,500 Foot (unit)#Historical origin, Roman feet, modern 2.2 km or 1.4 miles). The origin is the ''(also:'' '')'', the league of Gaul. Argentina The Argentine league () is or 6,666 : 1 is . England On land, the league is most commonly defined as three miles (4.83 km), although the length of a mile could vary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mile
The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a imperial unit, British imperial unit and United States customary unit of length; both are based on the older English unit of Unit of length, length equal to 5,280 Foot (unit), English feet, or 1,760 yards. The statute mile was standardised between the Commonwealth of Nations and the United States by an international yard and pound, international agreement in 1959, when it was formally redefined with respect to SI units as exactly . With qualifiers, ''mile'' is also used to describe or translate a wide range of units derived from or roughly equivalent to the #Roman, Roman mile (roughly ), such as the #Nautical, nautical mile (now exactly), the #Italian, Italian mile (roughly ), and the li (unit), Chinese mile (now exactly). The Romans divided their mile into 5,000 (), but the greater importance of furlongs in the Kingdom of England#Tudor period, Elizabethan-era England meant th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot (unit)
The foot (standard symbol: ft) is a Units of measurement, unit of length in the imperial units, British imperial and United States customary units, United States customary systems of metrology, measurement. The prime (symbol), prime symbol, , is commonly used to represent the foot. In both customary and imperial units, one foot comprises 12 inches, and one yard comprises three feet. Since international yard and pound, an international agreement in 1959, the foot is defined as equal to exactly 0.3048 meters. Historically, the "foot" was a part of many local systems of units, including the Ancient Greek units of measurement, Greek, Ancient Roman units of measurement, Roman, Chinese units of measurement, Chinese, Units of measurement in France before the French Revolution, French, and English units, English systems. It varied in length from country to country, from city to city, and sometimes from trade to trade. Its length was usually between 250 mm and 335 mm and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
