How many miles is a kilometer, how many meters is a mile, what are other units of length, and how to calculate them! ! !

China traditional unit of length.

▲ The traditional length units in China are Li, Zhang, ruler, inch and Li.

1 Li = 150 sheets = 500m.

2 Li = 1 km (1000m)

1 ft = 10 ft,

1 foot = 10 inch.

1 inch = 10 point.

1 = 10%.

1 sheet = 3.33m,

1 ft =3.33 decimeters,

1 inch =3.33 cm.

International standard unit of length

▲ In the international system of units, the standard unit of length is "meter", which is represented by the symbol "m". 1960 The 1st International Metrology Conference: "The length of the meter is equal to 1650763.73 times of the radiation wavelength passing between 2P 10 and 5d 1 levels of krypton -86 atoms in vacuum".

▲ Other length units include: light year, meter (Pm), megameter (mm), kilometer (km), decimeter (dm), centimeter (cm), millimeter (Mm), silk rice (dmm), millet (cmm), micron (micron), nanometer (nm) and so on. Their conversion relationship with rice is as follows:

1ym =1×10 24m (Yao Mi)

1zm = 1× 10 2 1m(zemi)

1em =1×1018m (Amy)

1 light year = 9.46× 10 15m (light year).

1pm =1×1015m (m)

1TM =1×1012m (too meters)

1GM =1×109m (Jimmy)

1 mm = 1× 10 meter (megameter)

1 km =1x10 3m (km)

1hm =1×10m (100m)

1 dam = 1× 10 1m( 10m)。

1 decimeter = 1× 10 (- 1) meter (decimeter)

1 cm = 1x 10 (-2) meters (cm)

1 mm = 1× 10 (-3) meters (mm)

1DMM =1×10 (-4) meters (silk rice)

1 CMM = 1× 10 (-5) m (Mi Hu)

1μ m =/kloc-0 /×10 (-6) meters (microns)

1 nm = 1× 10 (-9) meter (nm)

1pm =1×10 (-12) meters (picometers)

1FM =1×10 (-15) meters (femtometers)

1am = 1× 10(- 18)m(Ami)

1zm =1×10 (-21) meters (meters)

1ym =1×10 (-24) meters (one meter)

In addition, a unit Egstrom (abbreviated as Egstrom, symbol? ) is a unit of length. It is not SI unit, but it can be converted by SI unit, that is, 1? = 10(- 10)m = 0. 1nm。 Generally used for atomic radius, bond length and visible light wavelength. For example, the average diameter of atoms (calculated by empirical radius) is between 0.5 angstrom (hydrogen) and 3.8 angstrom (uranium, the heaviest natural element). It is also widely used in structural biology. Egstrom was named in memory of Swedish scientist Anders ngstrm. Egstrom is one of the founders of spectroscopy. He made a spectrogram for the radiation wavelength of the solar spectrum in 10 (- 10) meters. He also studied heat conduction, geomagnetism and Northern Lights (which are very important for him to ski in the Arctic).

A British unit of length used in a few European and American countries.

A few European and American countries, mainly Britain and the United States, use English units, so they use different units of length, mainly miles, yards, feet and inches.

Mile 1 mile = 1760 yards =5280 feet = 1.609344 kilometers.

Code (yd) 1 code =3 feet = 0.9144m.

Father (f, fa) 1 father =2 yards =1.8288m.

Furong 1 wave =220 yards =20 1. 17 meters.

Feet (ft) 1 foot = 12 inch =30.48 cm.

Inch 1 inch = 2.54cm.

A unit of length commonly used in astronomical observation

▲ In astronomy, "light year" is often used as the unit of length, which is the distance traveled by light in vacuum 1 year, so it is also called light year.

1 light year = 9.4653×1012km.

But it is customary to say that light years are units of distance.

Another commonly used unit of length is "parsec", which refers to the distance with annual parallax of 1 second.

1 parsec =3.26 16 light years.

In addition, there is a commonly used length unit "astronomical unit".

1 astronomical unit ≈ 65438+496 million kilometers

Brief introduction of length unit

light-year

Light years, units of length, and light years are generally used to calculate the distance between stars. Light-year refers to the distance that light travels in a vacuum for one year (that is, 365.25 days, while a day is equivalent to 86,400 seconds, and a year is 31.557,600 seconds), which is calculated by time and speed.

The distance traveled by light in a year is called "a light year". A light-year is about 9.46x1012km. A more formal definition is: the distance a photon travels in a year in free space and at an infinite distance from any gravitational or magnetic field. Because the speed of light in a vacuum is 299,792,458 meters per second (exact value), one light year is 9,460,730,472,580,800 meters, that is, 5,878,897,965,438+05,665,438+0.709 miles. )

(Note: 1 km = 0.6214 mile = 0.540 nautical mile; 1 Julian year = 3 1557600 seconds. )

Light years are usually used to measure long distances, such as the distance between the solar system and another star. Light years are not units of time. In astronomy, the second difference is another commonly used unit, 1 second difference =3.26 light years.

astronomical unit

Astronomical unit (AU) is a unit of length, which is approximately equal to the average distance from the earth to the sun. One of astronomical constants. The basic unit for measuring distance in astronomy, especially the distance between celestial bodies in the solar system. The average distance from the earth to the sun is an astronomical unit. An astronomical unit is about 65438+496 million kilometers. 1976, the international astronomical union defined an astronomical unit as the distance between a particle with negligible mass and undisturbed orbit, and an object with a period of revolution of 365.983 days (that is, one gauss year) and a mass of about one sun. At present, the recognized astronomical unit is149,597,870,69130m (about/kloc-0.5 billion kilometers or 93 million miles).

When the astronomical unit was first used, its actual size was not very clear, but the distance between planets could be calculated by heliocentric geometry and the laws of planetary motion. Later, through parallax and modern radar, the actual size of astronomical units was finally found accurately. However, due to the uncertainty of the gravitational constant (only five or six significant bits), the mass of the sun cannot be very accurate. If the position of the planet is calculated in international units, its accuracy will inevitably decrease in the process of unit conversion. Therefore, these calculations are usually based on solar mass and astronomical units, not kilograms and kilometers.

The distance of one astronomical unit. It is equivalent to the average distance from the earth to the sun, about 1.496× 10⒏km.

parsec

Parsec (English Parsec, abbreviated as pc) is a unit of length in astronomy. Parsec is one of the oldest and most standard methods to measure the distance between stars. It is based on triangle parallax. The inner angle of a triangle with the average radius of the earth's orbit (one astronomical unit, AU) as the base is called parallax. When the size of this angle is 1 s, the length of one side of this triangle (because the length difference between the two sides corresponding to 1 s can be completely ignored, this triangle can be imagined as a right triangle or an isosceles triangle) is called 1 parsec.

Parsec is mainly used to measure the distance of celestial bodies outside the solar system. The difference of 1 sec is defined as the distance when the annual parallax of celestial bodies is 1 ". Parsec is the reciprocal of annual parallax. When the annual parallax of the celestial body is 0. 1, the distance is 10 parsec, and when the annual parallax of the celestial body is 0.0 1, the distance is 100 parsec, and so on. 1 parsec is equal to 3.26 164 light years, or 206,265 astronomical units, or 30.8568 trillion kilometers. When measuring distant galaxies, the parsec unit is too small, usually using thousands of parsec (kpc) and millions of parsec.

Astronomers usually use parsec instead of astronomical units to describe the distance of celestial bodies. This is not only because the parsec number is easier to calculate, but also because of historical reasons. The greater the parallax of celestial bodies, the closer the distance is. On the contrary, the smaller the parallax, the farther away from us. The nearest star (except the sun) is about 1.29pc(4.22 light years), which lies in the parsec of proxima centauri. One parsec is equal to 308359979628 19660.8 meters. 1 parsec =3.26 16 light years =206265 astronomical unit =308568 million kilometers.

Paimi

The meter is also one of the units for measuring distance. It is sometimes used to measure small distances in the universe.

The representative symbol is Pm. 1Pm= 10 to the power of 15 m (m), i.e. 1Pm= 1, 000,000,000,000,000 m (i.e. 1 trillion km or/.

megametre

A unit of measurement for length.

Symbol: millimeter (not to be confused with millimeter symbol)

Nickname: Makami

Conversion relation:1mm =1000m =100000m.

Megameter (symbol Mm) is a rare unit of length, which is approximately equal to 62 1.37 miles. This unit is rarely used for two reasons:

One is that on this large scale, there are usually more suitable units, such as kilometers or astronomical units, which can also be expressed by scientific notation;

Secondly, the symbol difference between megameter and millimeter is only uppercase "M" and lowercase "M", and many people will confuse the two.

The following are several megameter lengths and distances that are available daily:

The circumference of the earth passing through the two poles is 39.94 Mm (according to the original definition of meter, from 179 1 year to 1875, the polar circumference of the earth is defined as 40.00 Mm (exactly). See the definition of rice for details. )

The distance from Amsterdam in the Netherlands to Bordeaux in France is about1mm.

The equatorial diameter of the earth is about 12.76 mm.

The average distance from the earth to the moon is 384.4 mm.

Saturn's equatorial diameter is143mm.

Kilometers (kilometers)

Also known as kilometer, it is a unit of length, code name km, which is usually used to measure the distance between two places.

transformational relation

1.6 1 km = 1 mile 1.6 1 km =1610m.

1 km (km) = 1 0,000m (m) =100,000m (cm) = 1 0,000mm (mm)

rice

The unit of length "meter" in the international system of units originated in France. 1790 In May, a special committee composed of French scientists suggested that one fortieth of the total length of the earth meridian passing through Paris should be used as the unit of length-meter, and 179 1 year was approved by the French Parliament. In order to make a benchmark to represent the value of rice, under the leadership of French astronomers Gerliangbule and Mishin, measurements were made from Dunkirk, France to Barcelona, Spain, and from 1792 to 1799. 1799, according to the measurement results, a platinum rice bar with a short section of 3.5mm× 25mm was made, and the distance between the two ends of the bar was set as 1m, which was kept by the French archives, so it was also called "archival rice". This is the earliest definition of rice.

Due to the serious deformation of archival rice, 1872 abandoned the definition of archival rice and used rice made of original platinum alloy (90% platinum, 10% iridium) as the length unit. The original rice cooker was made according to the length of "file rice". At that time, * * * made 3 1 piece, the cross section was approximately X-shaped, and the length of the archive meter was engraved on the groove (neutral surface) of the ruler with two 6-8 micron wide scribes. 1889 At the First International Metrology Conference, the prototype of No.6 meter identified by the International Bureau of Metrology (one of the prototype of 3 1 meter which is closest to the length of the file meter at 0℃) was selected as the international rice prototype, which was kept as the most authoritative length benchmark in the world in the basement of the International Bureau of Metrology in Paris, and the remaining rulers were distributed to the participating countries as auxiliary rulers. It is stipulated that when the ambient air temperature is 0℃, the distance between the two ends of the rice cooker is 1m. 1927. The definition of rice was strictly stipulated in the Seventh International Metrology Conference. In addition to the temperature requirement, it is also proposed that the raw rice container should be kept at the standard atmospheric pressure 1, and its placement method is specified in detail.

However, there are many shortcomings in taking rice as the objective standard of rice, such as material deformation; The measurement accuracy is not high (only 0. 1 micron). It is difficult to meet the needs of precise measurement such as metrology. In addition, if the original rice cooker is damaged, there will be no basis for copying, especially it is difficult to ensure that the replica is completely consistent with the original rice cooker, which brings difficulties to the use of various countries. Therefore, the idea of using natural values as unit benchmarks has always been desired by people. In 1950s, with the development of isotope spectrum light source. The narrow Krypton -86 isotope spectrum was discovered. With the success of interference technology, people finally found a natural standard that is not easy to be destroyed, that is, the natural standard with the wavelength of light wave as the length unit.

1960 The definition of meter was changed to: "The length of meter is equal to 1650763.73 times of the radiation wavelength passing between 2P 10 and 5d 1 levels of krypton -86 atoms in vacuum. This natural benchmark has stable performance, no deformation problem, easy replication and high replication accuracy. China also established the krypton -86 isotope length standard in 1963. After the definition of rice is changed, the original international rice instruments are still kept in the International Bureau of Metrology according to the original regulations.

With the progress of science and technology, since the 1970s, the measurement of time and the speed of light has reached a high precision. Therefore, 1983, 10 adopted a new definition of the meter at the 17th international metrology conference held in Paris in June: "the meter is the length of light propagating in a vacuum with a time interval of 1/299792458 seconds". In this way, the definition of meter based on spectral line wavelength is replaced by the new definition of meter.

In fact, the definition of meter is the distance traveled by light measured by platinum atomic clock in O.000000003335640952 seconds (this special number is taken because it corresponds to the historical definition of meter-according to the distance between two scales on a specific platinum rod preserved in Paris). Similarly, we can use a more convenient unit of length called light seconds, which is simply defined as the distance that light travels in one second. Now in the theory of relativity, we define the distance according to time and the speed of light, so that every observer can automatically measure the same speed of light (defined as every 0.0000000335640952 seconds 1 meter). There is no need to introduce the concept of ether, because Michelson-Morey experiment shows that the existence of ether can't be detected anyway. However, the theory of relativity forces us to fundamentally change our concept of time and space. We must accept the view that time cannot be completely divorced from and independent of space, but must be combined with space to form the so-called space-the object of time.

decimetre

Decimeter or dm is one of the metric units of length, and 1 decimeter is equivalent to one tenth of 1 meter.

Transformation relation:

0.000 1 km = 1 decimeter

0. 1 meter (m) = 1 decimeter

10cm = 1 decimeter

100 mm = 1 decimeter

10 decimeter = 1 meter (meter)

0. 1 decimeter = 1 cm

0.0 1 decimeter = 1 millimeter (mm)

centimetre

Centimeter in English. The abbreviation (symbol) is cm.

About centimeter unit conversion:

1 cm = 10/0mm =0. 1 decimeter =0.0 1 m =0.0000 1 km.

millimetre

English abbreviation MM (or mm, ㎜)

Series relation

1mm = 0. 1cm；

=0.0 1 decimeter;

= 0.00 1m；

=0.00000 1 km

Millimeter, also known as millimeter (or millimeter), is a unit of length and rainfall, and the symbol is ㎜. 1mm is equivalent to one thousandth of 1mm (this means "milli").

decimetre

Silk meter, unit of length

Abbreviation: dmm.

1 sago =110,000m

(1) Calculate tiny units of length, capacity and weight.

(2) Traces of length or weight. Ten is a trace, and ten is a dime.

centimillimetre

Mi Hu, unit of length.

Abbreviation: cmm

1 Mi Hu =1100000m.

1 Mi Hu = 10 micron.

1 Mi Hu =0. 1 silk.

1 Mi Hu =0.0 1 mm.

micron

Micron is a unit of length, and the symbol [micron] is pronounced [miu]. 1 micron is equivalent to one millionth of 1 meter.

Transformation relation:

1 000 000 picometers (pm) = 1 micron (micron)

1 000 nanometer (nm) = 1 micron (micron)

0.00 1 mm = 1 micron (micron)

0.000 1 cm =1μ m.

0.000 0 1 decimeter (dm) = 1 micron (micron)

0.000 00 1 meter (m) = 1 micron (micron)

0.000 000 00 1 km =1μ m.

0.000 00 1 micron (micron) = 1 picometer (pm)

0.00 1 micron (micron) = 1 nanometer (nanometer)

1 000 micron = 1 mm

10 000 micron = 1 cm.

100 000 micron (micron) = 1 decimeter (decimeter)

1 000 000 micron (micron) = 1 meter (meter)

1 000 000 000 μ m = 1 km

nanometre

Nanometer (symbol is nm) is the unit of length, originally called nanometer, that is, 10-9 meters (65438+ billionth of a meter). Like centimeters, decimeters and meters, it is a unit of measurement for length. It is four times the size of an atom and less than the length of a single bacterium. A single bacterium is invisible to the naked eye, and the diameter measured by microscope is about five microns. For example, suppose that the diameter of a hair is 0.05 mm, and it is cut into 50,000 pieces on average in the radial direction, and the thickness of each piece is about one nanometer. That is to say, one nanometer is about 0.00000 1 mm. Nanoscience and technology, sometimes called nanotechnology, is to study the properties and applications of materials with structural dimensions between 1 and 100 nm.

Pimi

Pimi or pm is the unit of length, and 1 pimi is equivalent to one trillion of 1 meter. Sometimes it is called a micron in atomic physics.

transformational relation

1 picometer = 10 (- 12) meters.

0.00 1 nm = 1 picometer

0.000 00 1 micron (micron) = 1 picometer

0.000 000 00 1 mm = 1 picometer.

1 000 picometer = 1 nanometer (nanometer)

1 000 000 picometers = 1 micron (micron)

1 000 000 000 picometers = 1 mm (mm)

Nanometer

The femto meter (or fm) is the unit of length, and 1 femto meter is equivalent to 10 minus 15 power meter. 10 femtometer is about the size of a nucleus.

transformational relation

0.00 1 picometer (pm) = 1 nanometer.

0.000 00 1 nanometer (nm) = 1 femtometer.

0.000 000 00 1 micron (? M) = 1 femtometer

0.000 000 000 00 1 mm = 1 nm.

1 000 femtometers = 1 picometers (pm)

1 000 000 femtometers = 1 nm.

1 000 000 000 femtometers = 1 micron (micron)

1 000 000 000 000 femtometers = 1 mm (mm)

Acute myocardial infarction (AMI)

Ami (attometer or am) is the unit of length, and 1 Ami is equivalent to 10 (- 18) meters.

transformational relation

0.00 1 femto meter (fm) = 1 Amy.

0.000 00 1 picometer (pm) = 1 Ami.

0.000 000 00 1 nm = 1 nm

0.000 000 000 00 1 micron (? M) = 1 Ami

1 000 Ami = 1 femto meter (fm)

1 000 000 Ami = 1 picometer (pm)

1 000 000 000 nm = 1 nm (nanometer)

1000 000 000 000 Amy =1micron (? M) length unit conversion table

Universal conversion table for metric and English length units

Kilometers. m. cm。 Miles and miles. Haili kt Code code. Feet, feet. Inches110005438+0000000008.50000000005+0100626 5438+00.0005 5396416076.2/kloc-0. 43830.9 143839 1.43830.0005680.000494 13360.0003040.30479430.47940.000 1890.00065438 +0640.333333 1 1 20.0000250.0253992.539950.0000 150.0000 130.0277770.088333 1

Prefix used to form decimal multiples and fractional units

Chinese prefix English prefix symbol 10 24 Yao [it] yotay1021ze [it] zettaz1018ai [Kesa] exae1kloc. Terat10.9 Gigag10.66 Megam10.33 Kilok10.22 HEC TOH1Kloc-0/Dikada/Kloc. Roμ10-9 nano10-12 pi [ke] picop10-/5 Fei [mother] femtof10-18 a.