|1 km in ...||... is equal to ...|
|SI units||1000 m|
|imperial/US units|| 0.62137 mi |
|nautical units||0.53996 nmi|
The kilometre (SI symbol: km; // or // ), spelt kilometer in American English, is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for 1000). It is now the measurement unit used for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the statute mile is the unit used.
The abbreviations k or K (pronounced // ) are commonly used to represent kilometre, but are not recommended by the BIPM. A slang term for the kilometre in the US and UK militaries is klick .
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There are two common pronunciations for the word.
The former follows a pattern in English whereby metric units are pronounced with the stress on the first syllable (as in kilogram, kilojoule and kilohertz) and the pronunciation of the actual base unit does not change irrespective of the prefix (as in centimetre, millimetre, nanometre and so on). It is generally preferred by the British Broadcasting Corporation (BBC) and the Australian Broadcasting Corporation (ABC).[ citation needed ]
Many scientists and other users, particularly in countries where the metric system is not widely used, use the pronunciation with stress on the second syllable.The latter pronunciation follows the stress pattern used for the names of measuring instruments (such as micrometer, barometer, thermometer, tachometer and speedometer). The contrast is even more obvious in countries using the Commonwealth spelling rather than American spelling of the word metre.
When Australia introduced the metric system in 1975, the first pronunciation was declared official by the government's Metric Conversion Board. However, the Australian prime minister at the time, Gough Whitlam, insisted that the second pronunciation was the correct one because of the Greek origins of the two parts of the word.
By a decree of 8 May 1790, the Constituent assembly ordered the French Academy of Sciences to develop a new measurement system. In August 1793, the French National Convention decreed the metre as the sole length measurement system in the French Republic. The first name of the kilometre was "Millaire". Although the metre was formally defined in 1799, the myriametre (10000 metres) was preferred to the "kilometre" for everyday use. The term "myriamètre" appeared a number of times in the text of Develey's book Physique d'Emile: ou, Principes de la science de la nature, (published in 1802), while the term kilometre only appeared in an appendix. French maps published in 1835 had scales showing myriametres and "lieues de Poste" (Postal leagues of about 4288 metres).
The Dutch, on the other hand, adopted the kilometre in 1817 but gave it the local name of the mijl. 1000 metres.It was only in 1867 that the term "kilometer" became the only official unit of measure in the Netherlands to represent
Two German textbooks dated 1842and 1848 respectively give a snapshot of the use of the kilometre across Europe: the kilometre was in use in the Netherlands and in Italy, and the myriametre was in use in France.
In 1935, the International Committee for Weights and Measures (CIPM) officially abolished the prefix "myria-" and with it the "myriametre", leaving the kilometre as the recognised unit of length for measurements of that magnitude.
Some sporting disciplines feature 1000 m (one-kilometre) races in major events (such as the Olympic Games). In some disciplines—although world records are catalogued—one-kilometre events remain a minority.
Kilometre world records (for various sporting disciplines):
|Running (M)||Noah Ngeny||2:11.96||Rieti, Italy||5 Sep 1999||Not an Olympic event|
|Running (F)||Svetlana Masterkova||2:28.98||Brussels||23 Aug 1996||Not an Olympic event|
|Speed Skating (M)||Shani Davis||1:06.42||Salt Lake City||7 Mar 2009|
|Speed Skating (F)||Cindy Klassen||1:13.11||Calgary||25 Mar 2006|
|Cycling (M)||Arnaud Tourant||58.875||La Paz, Bolivia||10 Oct 2001||No official 1000 m women's record|
The kilogram is the base unit of mass in the metric system, formally the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering, and commerce worldwide, and is often simply called a kilo in everyday speech.
The litre or liter is a non-SI unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre. A cubic decimetre occupies a volume of 10 cm × 10 cm × 10 cm and is thus equal to one-thousandth of a cubic metre.
The metre or meter is the base unit of length in the International System of Units (SI). The SI unit symbol is m. The metre is defined as the length of the path travelled by monochromatic light in a vacuum in 1/299 792 458 of a second. The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately 40000 km. In 1799, the metre was redefined in terms of a prototype metre bar. In 1960, the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and slightly updated in 2019.
Metrication or metrification is the act or process of converting the system of measurement traditionally used in a country to the metric system. All over the world, nations have transitioned from their local and traditional units of measurement to the metric system. This process first began in France during the 1790s and continues more than two centuries later, and the metric system has not been fully adopted in all countries and sectors.
The micrometre or micrometer, also commonly known by the previous deprecated name micron, is an SI derived unit of length equalling 1×10−6 metre ; that is, one millionth of a metre.
The Metre Convention, also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations. The treaty created the International Bureau of Weights and Measures (BIPM), an intergovernmental organization under the authority of the General Conference on Weights and Measures (CGPM) and the supervision of the International Committee for Weights and Measures (CIPM), that coordinates international metrology and the development of the metric system.
The International System of Units is the modern form of the metric system. It is the only system of measurement with an official status in nearly every country in the world. It comprises a coherent system of units of measurement starting with seven base units, which are the second, metre, kilogram, ampere, kelvin, mole, and candela. The system allows for an unlimited number of additional units, called derived units, which can always be represented as products of powers of the base units. Twenty-two derived units have been provided with special names and symbols. The seven base units and the 22 derived units with special names and symbols may be used in combination to express other derived units, which are adopted to facilitate measurement of diverse quantities. The SI system also provides twenty prefixes to the unit names and unit symbols that may be used when specifying power-of-ten multiples and sub-multiples of SI units. The SI is intended to be an evolving system; units and prefixes are created and unit definitions are modified through international agreement as the technology of measurement progresses and the precision of measurements improves.
A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit. While all metric prefixes in common use today are decadic, historically there have been a number of binary metric prefixes as well. Each prefix has a unique symbol that is prepended to the unit symbol. The prefix kilo-, for example, may be added to gram to indicate multiplication by one thousand: one kilogram is equal to one thousand grams. The prefix milli-, likewise, may be added to metre to indicate division by one thousand; one millimetre is equal to one thousandth of a metre.
The tonne is a non-SI metric unit of mass equal to 1,000 kilograms. It is commonly referred to as a metric ton in the United States. It is equivalent to approximately 2,204.6 pounds, 1.102 short tons (US) or approximately 0.984 long tons (UK). The official SI unit is the megagram, a less common way to express the same mass.
A metric system is a system of measurement that succeeded the decimalised system based on the metre introduced in France in the 1790s. The historical development of these systems culminated in the definition of the International System of Units (SI), under the oversight of an international standards body.
Metrology is the scientific study of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France, when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th Conference Generale des Poids et Mesures (CGPM) in 1960.
The foot is a unit of length in the imperial and US customary systems of measurement. Since the International Yard and Pound Agreement of 1959, one foot is defined as 0.3048 meter exactly. In customary and imperial units, one foot comprises 12 inches and three feet comprise one yard.
Myria- (symbol my) is a now obsolete decimal metric prefix denoting a factor of 104 (ten thousand). It originates from the Greek μύριοι (mýrioi) (myriad). The prefix was part of the original metric system adopted by France in 1795, but was not adopted when the SI prefixes were internationally adopted by the 11th CGPM conference in 1960.
Mesures usuelles were a French system of measurement introduced by Napoleon I in 1812 to act as compromise between the metric system and traditional measurements. The system was restricted to use in the retail industry and continued in use until 1840, when the laws of measurement from the 1795 and 1799 were reinstituted.
France has a unique history of units of measurement due to the radical decision to invent and adopt the metric system after the French Revolution.
The kilometre per hour is a unit of speed, expressing the number of kilometres travelled in one hour.
The hectare is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectare and one hectare contains about 2.47 acres.
The history of the metric system began in the Age of Enlightenment with notions of length and weight taken from natural ones, and decimal multiples and fractions of them. The system became the standard of France and Europe in half a century. Other dimensions with unity ratios were added, and it went on to be adopted by the world.
The metric system was developed during the French Revolution to replace the various measures previously used in France. The metre is the unit of length in the metric system and was originally based on the dimensions of the earth, as far as it could be measured at the time. The litre, is the unit of volume and was defined as one thousandth of a cubic metre. The metric unit of mass is the kilogram and it was defined as the mass of one litre of water. The metric system was, in the words of French philosopher Marquis de Condorcet, "for all people for all time".
The following outline is provided as an overview of and topical guide to the metric system – various loosely related systems of measurement that trace their origin to the decimal system of measurement introduced in France during the French Revolution.