metric system

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See also: Prefixes for Basic Metric Units (table)Prefixes for Basic Metric Units

Multiples
Prefix Abbreviation Power of 10 Equivalent
deka- or deca- da 101 ten
hecto- h 102 hundred
kilo- k 103 thousand
mega- M 106 million
giga- G 109 billion
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metric system,

system of weights and measuresweights and measures,
units and standards for expressing the amount of some quantity, such as length, capacity, or weight; the science of measurement standards and methods is known as metrology.

Crude systems of weights and measures probably date from prehistoric times.
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 planned in France and adopted there in 1799; it has since been adopted by most of the technologically developed countries of the world. It is based on a unit of length, called the metermeter,
abbr. m, fundamental unit of length in the metric system. The meter was originally defined as 1/10,000,000 of the distance between the equator and either pole; however, the original survey was inaccurate and the meter was later defined simply as the distance between two
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 (m), and a unit of mass, called the kilogramkilogram,
abbr. kg, fundamental unit of mass in the metric system, defined as the mass of the International Prototype Kilogram, a platinum-iridium cylinder kept at Sèvres, France, near Paris.
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 (kg).

The system has changed somewhat since it was first developed; e.g., the definition of the meter has changed, and the unit for mass is different. The meter was originally intended to be 1-10,000,000 of the distance on the earth's surface between the equator and either pole; however, because of errors in the original survey for determining the meter and because of the impracticality of referring to such a standard, the meter was later redefined in terms of the standard prepared and kept at Sèvres, France, near Paris. Long defined as the distance between two scratches on a bar of platinum-iridium alloy, the meter in 1960 was first redefined in terms of an atomic standard. In 1983 the meter was officially redefined as the distance traveled by light in vacuum during 1-299,792,458 of a second.

The original unit of mass, the gramgram,
abbr. g, unit of mass equal to 0.001 kilogram, the basic unit of mass in the metric system. The gram is the unit of mass in the cgs system. It is approximately equal to 0.035 avoirdupois ounce, or 0.0022 pound; a 1-pound mass equals about 453.6 grams.
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, was first defined as the mass of pure water at maximum density that would fill a cube whose edges are each 0.01 m. The unit of mass is now the kilogram, defined as the mass of a platinum-iridium cylinder kept at Sèvres. (A gram is now defined as a mass 1-1,000 kg.) Other metric units can be defined in terms of the meter and the kilogram. For example the are, the unit of area, is equal to the area of a square whose edges are each 10 m long. The liter, the metric unit of volume, is equal to the volume of a cube whose edges are each 1-10 m long.

Fractions and multiples of the metric units are related to each other by powers of 10, allowing conversion from one unit to a multiple of it simply by shifting a decimal point, and avoiding the lengthy arithmetical operations required by the English units of measurement. Standard prefixes (found in the table entitled Prefixes for Basic Metric UnitsPrefixes for Basic Metric Units

Multiples
Prefix Abbreviation Power of 10 Equivalent
deka- or deca- da 101 ten
hecto- h 102 hundred
kilo- k 103 thousand
mega- M 106 million
giga- G 109 billion
..... Click the link for more information.
) have been accepted for designating multiples and fractions of the meter, gram, are, and other units. Thus, 1,000 grams are a kilogram, 100 ares are a hectarehectare
, abbr. ha, unit of area in the metric system, equal to 10,000 sq m, or about 2.47 acres.
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, and 1-100 of a meter is a centimeter.

Several other systems of units based on the metric system have been in wide use. The cgs systemcgs system,
system of units of measurement based on the metric system and having the centimeter of length, the gram of mass, and the second of time as its fundamental units. Other cgs units are the dyne of force and the erg of work or energy.
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 is based on the centimeter of length, the gram of mass, and the secondsecond,
abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the day varies, however, the second must be defined in more precise terms.
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 of time. The mks systemmks system,
system of units of measurement based on the metric system and having the meter of length, the kilogram of mass, and the second of time as its fundamental units. Other mks units include the newton of force, the joule of work or energy, and the watt of power.
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 is based on the meter of length, the kilogram of mass, and the second of time. Units in the mks system are larger than the corresponding cgs units. Electric and magnetic unitselectric and magnetic units,
units used to express the magnitudes of various quantities in electricity and magnetism. Three systems of such units, all based on the metric system, are commonly used.
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 have been defined for both of these systems; in fact, two different sets of electric units are defined in the cgs system. The mks system serves as the basis for the International System of UnitsInternational System of Units,
officially called the Système International d'Unités, or SI, system of units adopted by the 11th General Conference on Weights and Measures (1960). It is based on the metric system.
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, a comprehensive system of units for all physical quantities adopted in 1960 by the 11th General Conference on Weights and Measures.

See also decimal systemdecimal system
[Lat.,=of tenths], numeration system based on powers of 10. A number is written as a row of digits, with each position in the row corresponding to a certain power of 10.
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.

Bibliography

See L. V. Judson, Weights and Measures Standards of the United States: A Brief History (1976; U.S. National Bureau of Standards Special Publication 447); K. Alder, The Measure of All Things (2002).

Metric system

A system of units used in scientific work throughout the world and employed in general commercial transactions and engineering applications in most of the developed nations of the world except for the United Kingdom and the United States. The basic units of the metric system define length (meter), mass (kilogram), and time (second).

The chief advantage of the metric system is that it is based on standards that have been accepted by international agreement, and it therefore provides a common basis for all scientific measurements. A second advantage of the metric system lies in the fact that only decimal multiples and submultiples of the fundamental length and mass units and of other derived units are employed. See Physical measurement, Time, Units of measurement

Metric System

 

(decimal system), a set of units for physical quantities based on the meter as the unit of length. Originally, the metric system also included units of area (the square meter), volume (the cubic meter), and weight (the kilogram; the weight of 1 cubic decimeter of water at 4°C), as well as the liter (for capacity), the are (for the area of plots of land), and the ton (1,000 kg). An important distinctive feature of the metric system was the method of forming multiple and fractional units in decimal ratios; the prefixes kilo-, hecto-, deca-, deci-, centi-, and milli- were adopted to form the names of the derived units.

The metric system was developed in France during the era of the French Revolution. According to a proposal by a commission of leading French scientists (J. Borda, M. Condorcet, P. Laplace, and G. Monge), the meter was adopted as the unit of length and made equal to one ten-millionth of one-quarter of the length of the geographical meridian passing through Paris. This decision resulted from the attempt to provide as a basis for the metric system an easily reproducible “natural” unit of length, which was related to some natural object that was for all practical purposes unchanging. The decree on the introduction of the metric system in France was passed on Apr. 7, 1795. In 1799 a platinum prototype meter was made and approved. The sizes, names, and definitions of the other units of the metric system were chosen in such a way that the system would have no national characteristics and could be adopted by all countries. The metric system became truly international in nature in 1875, when 17 countries, including Russia, signed the Metric Treaty for the provision of international standardization and the improvement of the metric system. The system was authorized for use in Russia (on an optional basis) by a law of June 4, 1899, which was drafted by D. I. Mendeleev, and it was made mandatory by a decree of the Council of People’s Commissars of the RSFSR on Sept. 14, 1918. It was made mandatory for the USSR by a resolution of the Council of People’s Commissars of the USSR on July 21, 1925.

An entire series of special systems of units covering only particular fields of physics and engineering, and also individual subsidiary units, has arisen on the basis of the metric system. The development of science, engineering, and international communications has led to the creation of the International System of Units, a unified system of units based on the metric system that covers all fields of measurement; it has now been made mandatory or is preferred by many countries.

REFERENCES

Isakov, L. D. Na vse vremena, dlia vsekh narodov. Petrograd, 1923.
Burdun, G. D. Edinitsy fizicheskikh velichin. Moscow, 1967.
Shirokov, K. P. “50-letie metricheskoi sistemy v SSSR.” IzmeriteVnaia tekhnika, 1968, no. 9.
Stille, U. Messen und Rechnen in der Physik. Braunschweig, 1961.

metric system

[′me·trik ‚sis·təm]
(mechanics)
A system of units used in scientific work throughout the world and employed in general commercial transactions and engineering applications; its units of length, time, and mass are the meter, second, and kilogram respectively, or decimal multiples and submultiples thereof.

metric system

any decimal system of units based on the metre. For scientific purposes the Syst?me International d'Unit?s (SI units) is used

metric system

A system of weights and measures that uses the gram, meter and liter as its primary units of weight, distance and capacity. The metric system is used all over the world except in the U.S., Liberia and Myanmar (formerly Burma). See space/time.

COMMON METRIC EQUIVALENTSGrams Pounds   Ounces

 gram              .0022      .04
 decagram   (10)   .0220      .35
 hectogram (100)   .2204     3.5
 kilogram (1000)  2.2046    35.3


 Liters

 1      =  1.06 quarts
 3.8    =  1 gallon


 Meters      Feet

 1 decameter   (10 m)      33
 1 hectometer (100 m)      328
 1 kilometer (1000 m)     3281


 Meters          Inches

 1 meter         39.37
 1 centimeter      .3937
 1 millimeter      .03937
 1 micrometer      .00003937
 1 nanometer       .00000003937
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