Meter: Forskelle mellem versioner
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m • Jeg har rettet punktummer, og rettet til store bogstaver efter punktum. • Jeg har rettet kommafejl • Jeg har også tilføjet ord til artiklen, for at gøre sætningerne færdige og forståelige. • Jeg har rettet nogle tal, hvor meningen var, at de skulle være procenttal, men hvor vedkommende personer, havde glemt at sætte en procenttegn efter tallet. • Længere nede ved ”Afledte enheder”, havde de glemt, at skrive enhed i slutningen, og derfor har jeg rettet det og tilføjet enhed på |
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One Meter (the symbol m) is a measure for the fundamental Si-units. One meter corresponds to the length of the distance the light travels in vacuum, over the period 1 / 299,792,458 seconds (thats about 0,0000000033564 second).
The metersystem was introduced to Denmark at a law, on May 4, 1907 with gradual entry into force between 1910 and 1916. The centenary of this was celebrated on April 1, 2012. The word meter comes from the French word mètre, which comes from the Greek metron (μέτρον), meaning "target".[[Fil:Den første meteren.jpg|thumb|Of the 16 marble stone marble erected around Paris in 1796 and 1797, this is the only one that remains in its original place, at Rue de Vaugirard 36 across from the Luxembourg Gardens.]]
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The meter has been defined since May 20, 2019 by allowing the fixed numerical value of the speed of light in vacuum, c, to be 299,792,458 when expressed in unit m / s, where the second is defined by the cesium transition rate Δν𝐂𝐬.
This definition, like the previous 1983 definition, means that "the meter is the length of the distance the light travels in vacuum in 1 / 299,792,458 seconds".
=== Previous Definitions ===
The meter was first defined by the French Academy of Sciences in 1791 as a ten millionth (1 / 10,000,000) of the distance from the Earth's geographical equator to the North Pole through Paris. In 1799 a platinum rod was manufactured as a prototype for the meter.
In order to spread the knowledge of the meteor as a new longitudinal measure, 16 marble blocks are set in various places in Paris, where the length of one meter was engraved.
In 1875, the meter convention was established and it formed a globally uniform system which later developed into SI units. In 1889, the original platinum bar was replaced by a bar with two engraved marks. The rod was made of an alloy consisting of 90% platinum and 10% iridium to make it more durable.
In the period from 1960 to 1983, the meter was defined as 1,650,763.73 times the wavelength of the radiation emitted from krypton-86 at the transition between two energy states. This meant that the meter was defined 50 times more accurately than the old platinum meter method.
In 1983, a meter was defined as the length of the path light travels in the empty space during the time 1 / 299,792,458 seconds.
=== Længde ===▼
== Derivative ==
* '''nanometer''' (symbol: nm) – 1/1.000.000.000 meter▼
The meter forms the basis for a large number of other units of measurement.
* '''millimeter''' (symbol: mm) – 1/1.000 meter▼
* '''centimeter''' (symbol: cm) – 1/100 meter▼
* '''kilometer''' (symbol: km) – 1.000 meter▼
With the usual SI prefixes, among other things,
<br />
* Micrometer (symbol: µm) - 1 / 1,000,000 meters (until 1960 alternatively referred to as microns and noted µ (my)).
* Millimeter (symbol: mm) - 1 / 1,000 meters
Here is a table of prefixes. The most frequently used are in bold:
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The series is supplemented by the allowable unit flow rate (10-10 m) which corresponds roughly to the diameter of a hydrogen atom.
One square meter (symbol: m²) corresponds to the area of a square with a side length of one meter. Similarly can be derived square centimeters (symbol: cm²), a square with side length of one centimeter (ie 1 / 10,000 m²), square kilometers (symbol: km², 1 million m²) and so on.
=== Areal ===▼
Volume
=== Volumen ===▼
<br />
One square meter (symbol: m²) corresponds to the area of a square with a side length of one meter. Similarly can be derived square centimeters (symbol: cm²), a square with side length of one centimeter (ie 1 / 10,000 m²), square kilometers (symbol: km², 1 million m²) and so on.
One cubic meter (symbol m³) corresponds to the volume of a cube (cube) with a side length of one meter. Similarly, cubic decimeters (symbol: dm³, 1/1000 m³, corresponding to one liter), cubic centimeters (symbol: cm³, 1 / 1,000,000 m³, corresponding to one milliliter) can be derived.
<br />
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|39.370
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|0.0254
|meter
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|<math>\approx</math>
|0.39370
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|2.54
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|<math>\approx</math>
|0.039370
|inches
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|1
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|25.4
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|<math>1*10^{10}</math>
|angstroms
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|<math>1*10^{-10}</math>
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|10
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|1
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|100
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"<math>\approx</math>" betyder "er circa lig med"▼
"=" betyder "lige ved definition" eller " er præcist lige med"▼
En meter er præcist ækvivalent til <math>\tfrac{5000}{127}</math>tommer og til <math>\tfrac{1250}{1143}</math>yard.▼
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<ref name="bipm9">Bureau International des Poids et Mesures (2019). [https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9-EN.pdf The International System of Units (SI)] 9. udgave, side 131. Citat: "The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum ''c'' to be 299 792 458 when expressed in the unit m s<sup>−1</sup>, where the second is defined in terms of the caesium frequency Δ𝝂<sub>𝐂𝐬</sub>."</ref>
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