Universal measure

The original proposal was expressed at the time by Professor of the University of Krakow S. Pudlovsky. His idea was that as a single measure one should take the length of the pendulum, which makes a full swing in one second. This proposal was published in the book "Universal Measure", published in Vilna in 1675 by his student T. Buratini. He also proposed to name meter unit of length.

Somewhat earlier, in 1673, the Dutch scientist H. Huygens published the brilliant work "Pendulum Clock", where he developed the theory of oscillations and described the construction of pendulum clocks. Based on this work, Huygens proposed his own universal measure of length, which he called hourly foot, and in size the hourly foot was equal to 1/3 of the length of the second pendulum. “This measure can not only be determined everywhere in the world, but can always be restored for all future ages,” Huygens wrote proudly.

However, there was one circumstance that confused scientists. The period of oscillation of the pendulum with the same length was different depending on geographical latitude, i.e., the measure, strictly speaking, was not universal.

Huygens' idea was propagated by the French geodesist Ch. Condamine, who proposed to base the measurement system on a unit of length corresponding to the length of a pendulum swinging once per second at the equator.

The French astronomer and mathematician G. Mouton also supported the idea of ​​a second pendulum, but only as a control apparatus, and G. Mouton proposed to put the principle of connection of a unit of measurement with the dimensions of the Earth as a basis for a universal system of measures, i.e., to take a part as a unit of length meridian arc length. This scientist also proposed to divide the measured part into tenths, hundredths and thousandths, that is, to use the decimal principle.

Metric

Projects for the reform of systems of measures have appeared in different countries, but this issue has been especially acute in France for the reasons listed above. Gradually, the idea of ​​creating a system of measures that meets certain requirements emerged:

- the system of measures should be unified and common;

- units of measurement must have strictly defined dimensions;

- there must be standards of units of measurement, unchanged in time;

- for each quantity there should be only one unit;

– units of different quantities should be related to each other in a convenient way;

– units must have submultiple and multiple values.

On May 8, 1790, the French National Assembly adopted a decree on the reform of the system of measures and instructed the Paris Academy of Sciences to carry out necessary work according to the above requirements.

Several commissions have been formed. One of them, led by academician Lagrange, recommended the decimal subdivision of multiples and submultiples of units.

Another commission, which included scientists Laplace, Monge, Borda and Condors, proposed to accept one forty-millionth part of the earth's meridian as a unit of length, although the vast majority of specialists, who know the essence case, I thought that the choice would be in favor of the second pendulum.

The decisive factor here was that a stable basis was chosen - the size of the Earth, the correctness and invariance of its shape in the form of a ball.

Commission member Ch. Borda, a geodesist and hydraulician, proposed calling the unit of length a meter; in 1792, he determined the length of a second pendulum in Paris.

On March 26, 1791, the National Assembly of France approved the proposal of the Paris Academy, and a temporary commission was formed for the practical implementation of the decree on the reform of measures.

On April 7, 1795, the National Convention of France passed a law on new weights and measures. It was accepted that meter- one ten-millionth part of a quarter of the earth's meridian passing through Paris. but at the same time, it was especially emphasized that the introduced unit of length in name and size did not coincide with any of the French units of length that existed at that time. Therefore, the possible further argument that France is “pushing through” its system of measures as an international one is ruled out.

Instead of temporary commissions, commissioners were appointed, who were instructed to carry out work on the experimental determination of units of length and mass. The famous scientists Berthollet, Borda, Brisson, Coulomb, Delambre, Gaui, Lagrange, Laplace, Méchain, Monge and others were among the commissioners.

Delambre and Méchain resumed work on measuring the length of the meridian arc between Dunkirk and Barcelona, ​​corresponding to the 9° 40′ sphere (later this arc was extended from the Shetland Islands to Algeria).

These works were completed by the autumn of 1798. Standards of the meter and kilogram were made of platinum. The standard meter was a platinum bar 1 meter long and 25 × 4 mm in section, i.e. it was end measure, and on June 22, 1799, the prototypes of the meter and kilogram were solemnly transferred to the Archives of France, and since then they have been called archival. But it must be said that even in France the metric system was not established immediately, traditions and inertia of thinking had a great effect. Napoleon, who became emperor of France, did not like the metric system, to put it mildly. He believed: “There is nothing more contrary to the mindset, memory and reason than what these scientists offer. The welfare of present generations has been sacrificed to abstractions and empty hopes, for in order to force the old nation to adopt new units of measures and weights, it is necessary to remake all the administrative rules, all the calculations of industry. Such work frightens the mind. In 1812, by decree of Napoleon, the metric system in France was abolished, and only in 1840 was it restored again.

Gradually, the metric system was adopted and introduced by Belgium, Holland, Spain, Portugal, Italy, a number of republics South America. The initiators of the introduction of the metric system in Russia were, of course, scientists, engineers, researchers, but tailors, seamstresses and milliners played a significant role - by that time, Parisian fashion had conquered high society, and there, mostly masters who came from abroad worked with their meters . It was from them that the still existing narrow strips of oilcloth matter - "centimeters", which are still in use, came from.

At the Paris Exhibition of 1867, the International Committee for Measures, Weights and Coins was created, which compiled a report on the benefits of the metric system. However, the report compiled in 1869 by Academicians O. V. Struve, G. I. Wild and B. S. Jacobi, sent on behalf of the St. Petersburg Academy of Sciences to the Paris Academy, had a decisive influence on the entire subsequent course of events. The report argued for the need to introduce an international system of weights and measures based on the metric system.

The proposal was supported by the Paris Academy, and the French government turned to all interested states with a request to send scientists to the International Metric Commission to solve practical problems. By that time, it turned out that the shape of the Earth is not a ball, but a three-dimensional spheroid (the average radius of the equator is 6,378,245 meters, the difference between the largest and smallest radii is 213 meters, and the difference between the average radius of the equator and the polar semi-axis is 21,382 meters). In addition, repeated measurements of the arc of the Parisian meridian gave the value of the meter somewhat lower than the value obtained by Delambre and Méchain. In addition, there is always the possibility that with the creation of more advanced measuring instruments and the emergence of new measurement methods, the measurement results will change. Therefore, the commission made an important decision: “The new prototype of the measure of length should be equal in size to the Archival meter,” that is, it should be an artificial standard.

The International Commission also adopted the following decisions.

1) The new prototype of the meter must be a line measure, it must be made of an alloy of platinum (90%) and iridium (10%) and have an X-shaped section.

2) In order to give the metric system an international character and ensure uniformity of measures, standards should be prepared and distributed among the countries concerned.

3) One standard, the closest in value to the Archival one, is accepted as international.

4) Instruct practical work on the creation of standards of the French section of the commission, since the archival prototypes are in Paris.

5) Appoint a permanent international committee of 12 members to direct the work.

6) Establish the International Bureau of Weights and Measures as a neutral scientific institution based in France.

In accordance with the decision of the commission, practical measures were taken and in 1875 an international conference was convened in Paris, at the last meeting of which, on May 20, 1875, the Meter Convention was signed. It was signed by 17 countries: Austria-Hungary, Argentina, Belgium, Brazil, Venezuela, Germany, Denmark, Spain, Italy, France, Peru, Portugal, Russia, USA, Turkey, Switzerland, Sweden and Norway (as one country). Three more countries (Great Britain, Holland, Greece), although they participated in the conference, did not sign the Convention because of disagreement on the functions of the International Bureau.

For the International Bureau of Weights and Measures, the Bretel Pavilion was assigned, located in the Saint-Cloud Park in the suburbs of Paris - Sevres, and soon a laboratory building with equipment was built near this pavilion. The activities of the Bureau are carried out at the expense of funds transferred by the countries - members of the Convention in proportion to the size of their population. At the expense of these funds, standards of the meter and kilogram (36 and 43, respectively) were ordered in England, which were made in 1889.

Meter standards

The meter standard was a platinum-iridium X-shaped rod 1020 mm long. On the neutral plane at 0 °C, three strokes were applied on each side, the distance between the middle strokes was 1 meter (Fig. 1.1). The standards were numbered and compared with the Archival meter. Prototype No. 6 turned out to be closest to the Archival one, and it was approved as an international prototype. Thus, the standard of the meter became artificial and represented dashed measure.

Four more witness standards were added to Standard No. 6 and they were retained by the International Bureau. The remaining standards were distributed by lot among the countries that signed the Convention. Russia got standards No. 11 and No. 28, and No. 28 was closer to the international prototype, so it became the national standard of Russia.

By decree of the Council of People's Commissars of the RSFSR of September 11, 1918, prototype No. 28 was approved as the state primary standard of the meter. In 1925, the Council of People's Commissars of the USSR adopted a resolution recognizing the Metric Convention of 1875 as valid for the USSR.

In 1957 - 1958 a scale with decimeter divisions was applied to the standard No. 6, the first decimeter was divided into 10 centimeters, and the first centimeter into 10 millimeters. After applying strokes, this standard was re-certified by the International Bureau of Weights and Measures.

The error in the transmission of a unit of length from the standard to the measuring instruments was 0.1 - 0.2 microns, which becomes clearly insufficient with the development of technology, therefore, in order to reduce the transmission error and obtain a natural indestructible standard, a new standard of the meter was created.

Back in 1829, the French physicist J. Babinet proposed to take the length of a certain line in the spectrum as a unit of length. However, the practical implementation of this idea occurred only when the American physicist A. Michelson invented the interferometer. Together with the chemist Morley E. Babinet J. published the work "On the method of using the wavelength of sodium light as a natural and practical standard of length", then he moved on to research isotopes: mercury - green and cadmium - red lines.

In 1927 it was accepted that 1 m equals 1553164.13 wavelengths of the red line of cadmium-114, this value was accepted as a standard along with the old prototype meter.

In the future, work was continued: in the USA, the spectrum of mercury was studied, in the USSR - cadmium, in the Federal Republic of Germany and France - krypton.

In 1960, the XI General Conference on Weights and Measures adopted the meter as a standard unit of length, expressed in wavelengths of light, and specifically, the inert gas Kr-86. Thus, the standard of the meter again became natural.

Meter is a length equal to 1650763.73 wavelengths in vacuum of radiation corresponding to the transition between the levels 2p 10 and 5d 5 of the krypton-86 atom. The old definition of the meter is canceled, but the prototypes of the meter remain and are stored in the same conditions.

In accordance with this decision, the State Primary Standard (GOST 8.020-75) was established in the USSR, which included the following components (Fig. 1.2):

1) source of primary reference radiation of krypton-86;

2) a reference interferometer used to study sources of primary reference radiation;

The accuracy of reproduction and transmission of a meter in light units is 1∙10 -8 m.

In 1983, the XVII General Conference on Weights and Measures adopted a new definition of the meter: 1 meter is a unit of length equal to the path traveled by light in vacuum in 1/299792458 of a second, i.e. the standard of the meter remains natural.

The composition of the standard meter:

1) source of primary reference radiation - a highly frequency-stabilized helium-neon laser;

2) a reference interferometer used to study sources of primary and secondary reference measurements;

3) a reference interferometer used to measure the length of line and end measures (secondary standards).

On the facade of the Ministry of Justice in Paris, under one of the windows, a horizontal line and the inscription "meter" are carved in marble. Such a miniature detail is barely noticeable against the backdrop of the majestic building of the Ministry and Place Vendôme, but this line is the only “meter standard” remaining in the city, which were located throughout the city more than 200 years ago in an attempt to introduce to the people a new universal system of measurements - metric.

We often take the system of measures for granted and do not even think about the history behind its creation. The metric system, which was invented in France, is official throughout the world, with the exception of three states: the United States, Liberia and Myanmar, although in these countries it is also used in some areas such as international trade.

Can you imagine what our world would be like if the system of measures was different everywhere, like the situation we are used to with currencies? But everything was like that before the French Revolution, which flared up at the end of the 18th century: then the units of measures and weights were different not only between individual states, but even within the same country. Almost every French province had its own units of measures and weights, incomparable with the units used by their neighbors.

The revolution brought a wind of change in this area: in the period from 1789 to 1799, activists sought to overturn not only the government regime, but also fundamentally change society, changing traditional foundations and habits. For example, in order to limit the influence of the church on public life, the revolutionaries introduced a new Republican calendar in 1793: it consisted of ten-hour days, one hour equaled 100 minutes, one minute equaled 100 seconds. This calendar was fully in line with the desire of the new government to introduce the decimal system in France. This approach to calculating time never caught on, but people came to like the decimal system of measures, which was based on meters and kilograms.

The first scientific minds of the Republic worked on the development of a new system of measures. The scientists intended to invent a system that would obey logic, and not local traditions or the wishes of the authorities. Then they decided to be based on what nature gave us - the reference meter had to be equal to one ten millionth of the distance from North Pole to the equator. This distance was measured along the Paris meridian, which passed through the building of the Paris Observatory and divided it into two equal parts.

In 1792, the scientists Jean-Baptiste Joseph Delambre and Pierre Mechain went along the meridian: the first was the city of Dunkirk in northern France, the second followed south to Barcelona. Using the latest equipment and the mathematical process of triangulation (a method of constructing a geodetic network in the form of triangles in which their angles and some of their sides are measured), they calculated to measure the meridian arc between two cities that were at sea level. Then, using the extrapolation method (method scientific research, consisting in extending the conclusions obtained from observation of one part of the phenomenon to another part of it), they were going to calculate the distance between the pole and the equator. According to the initial idea, the scientists planned to spend a year on all measurements and the creation of a new universal system of measures, but in the end the process dragged on for seven whole years.

Astronomers were faced with the fact that in those turbulent times, people often perceived them with great caution and even hostility. In addition, without the support of the local population, scientists were often not allowed to work; there were times when they were injured while climbing highest points in the district like the domes of churches.

From the top of the dome of the Pantheon, Delambre took measurements in Paris. Initially, King Louis XV erected the building of the Pantheon for the church, but the Republicans equipped it as the central geodetic station of the city. Today, the Pantheon serves as a mausoleum for the heroes of the Revolution: Voltaire, Rene Descartes, Victor Hugo, and others. In those days, the building also served as a museum - all the old standards of measures and weights that were sent by the inhabitants of France in anticipation of a new perfect system were stored there.

Unfortunately, despite all the efforts of scientists spent on developing a worthy replacement for the old units of measurement, no one wanted to use new system. People refused to forget the usual ways of measuring, which were often closely connected with local traditions, rituals and way of life. For example, ale - a unit of measure for cloth - was usually equal to the size of looms, and the size of arable land was calculated solely in days that needed to be spent on it.

The Parisian authorities were so outraged by the refusal of the inhabitants to use the new system of measures that they often sent police to local markets to force them into circulation. As a result, in 1812 Napoleon abandoned the policy of introducing the metric system - it was still taught in schools, but people were allowed to use the usual units of measure until 1840, when the policy was resumed.

It took almost a hundred years for France to completely switch to the metric system. This finally succeeded, but not thanks to the persistence of the government: France was moving rapidly in the direction of the industrial revolution. In addition, it was necessary to improve maps of the area for military purposes - this process required accuracy, which was not possible without a universal system of measures. France confidently entered the international market: in 1851, the first International Fair took place in Paris, where the participants of the event shared their achievements in the field of science and industry. The metric system was simply necessary to avoid confusion. erection eiffel tower 324 meters high was dedicated to the International Fair in Paris in 1889 - then it became the tallest man-made structure in the world.

In 1875, the International Bureau of Weights and Measures was established, headquartered in a quiet suburb of Paris - in the city of Sèvres. The Bureau maintains international standards and the unity of seven measures: meter, kilogram, second, ampere, Kelvin, Mole and Candela. A platinum standard meter is stored there, from which standard copies were carefully made and sent to other countries as a sample. In 1960, the General Conference of Weights and Measures adopted a definition of the meter based on the wavelength of light - thus making the standard even closer to nature.

At the headquarters of the Bureau there is also a kilogram standard: it is located in an underground storage under three glass caps. The standard is made in the form of a cylinder of an alloy of platinum and iridium, in November 2018 the standard will be revised and redefined using Planck's quantum constant. Audit Resolution international system units was adopted back in 2011, however, due to some technical features of the procedure, its implementation was not possible until recently.

Determining the units of measures and weights is a very time-consuming process, which is accompanied by various difficulties: from the nuances of conducting experiments to financing. The metric system underlies progress in many fields: science, economics, medicine, etc., it is vital for further research, globalization and improvement of our understanding of the universe.

In 1795, the Law on New Measures and Weights was passed in France, which established a single unit of length - meter, equal to ten millionths of a quarter of the arc of the meridian passing through Paris. Hence the name of the system - metric.

A platinum rod one meter long and of a very strange shape was chosen as the standard of the meter. Now the size of all rulers, one meter long, had to correspond to this standard.

Units installed:

- liter as a measure of the capacity of liquid and granular bodies, equal to 1000 cubic meters. centimeters and containing 1 kg of water (at 4 ° heat Celsius),

- gram as a unit of weight (the weight of pure water at a temperature of 4 degrees Celsius in the volume of a cube with an edge of 0.01 m),

- ar as a unit of area (the area of ​​a square with a side of 10 m),

- second as a unit of time (1/86400 of a mean solar day).

Later, the basic unit of mass became kilogram. The prototype of this unit was a platinum weight, which was placed under glass flasks and the air was pumped out - so that dust would not get in and the weight would not increase!

The prototypes of the meter and kilogram are still kept in the National Archives of France and are called "Meter Archive" and "Kilogram Archive" respectively.

There were different measures before, but an important advantage of the Metric system of measures was its decimality, since submultiple and multiple units, according to the accepted rules, were formed in accordance with the decimal count using decimal factors, which correspond to the prefixes deci, - centi, - milli, - deca, - hecto- and kilo-.

Currently, the metric system of measures is adopted in Russia and in most countries of the world. But there are other systems as well. For example, the English system of measures, in which the foot, pound and second are taken as the main units.

It is interesting that in all countries there are familiar packaging for different foods and drinks. In Russia, for example, milk and juices are usually packaged in liter bags. And large glass jars - entirely three-liter!

Remember: on professional drawings, the dimensions (dimensions) of products are signed in millimeters. Even if these are very large products, like cars!

Volkswagen Cady.

Citroen Berlingo.

Ferrari 360.

international decimal system measurement, which is based on the use of units such as kilogram and meter, is called metric. Varied Options metric system developed and used over the past two hundred years, and the differences between them consisted mainly in the choice of basic, basic units. On this moment almost universally used so-called International system of units (SI). Those elements that are used in it are identical all over the world, although there are differences in some details. International system of units very widely and actively used all over the world, and both in Everyday life as well as in scientific research.

For now Metric used in most countries of the world. There are, however, several large states in which to this day the English system of measures based on such units as the pound, foot and second is used. These include the UK, US and Canada. However, these countries have also already adopted several legislative measures aimed at moving towards Metric.

She herself originated in the middle of the XVIII century in France. It was then that scientists decided that they should create system of measures, which will be based on units taken from nature. The essence of this approach was that they constantly remain unchanged, and therefore the whole system as a whole will be stable.

Measures of length

• 1 kilometer (km) = 1000 meters (m)
• 1 meter (m) = 10 decimeters (dm) = 100 centimeters (cm)
• 1 decimeter (dm) = 10 centimeters (cm)
• 1 centimeter (cm) = 10 millimeters (mm)

Measures of area

• 1 sq. kilometer (km 2) \u003d 1,000,000 sq. meters (m 2)
• 1 sq. meter (m 2) \u003d 100 square meters. decimeters (dm 2) = 10,000 sq. centimeters (cm 2)
• 1 hectare (ha) = 100 aram (a) = 10,000 sq. meters (m 2)
• 1 ar (a) \u003d 100 square meters. meters (m 2)

Measures of volume

• 1 cu. meter (m 3) \u003d 1000 cubic meters. decimeters (dm 3) \u003d 1,000,000 cubic meters. centimeters (cm 3)
• 1 cu. decimeter (dm 3) = 1000 cu. centimeters (cm 3)
• 1 liter (l) = 1 cu. decimeter (dm 3)
• 1 hectoliter (hl) = 100 liters (l)

Measures of weight

• 1 ton (t) = 1000 kilograms (kg)
• 1 centner (c) = 100 kilograms (kg)
• 1 kilogram (kg) = 1000 grams (g)
• 1 gram (g) = 1000 milligrams (mg)

Metric

It should be noted that the metric system of measure was not immediately recognized. As for Russia, in our country it was allowed to be used after it signed Metric convention. At the same time, this system of measures for a long time it was used in parallel with the national one, which was based on such units as the pound, sazhen and bucket.

Some old Russian measures

Measures of length

• 1 verst = 500 fathoms = 1500 arshins = 3500 feet = 1066.8 m
• 1 fathom = 3 arshins = 48 vershoks = 7 feet = 84 inches = 2.1336 m
• 1 arshin = 16 inches = 71.12 cm
• 1 inch = 4.450 cm
• 1 foot = 12 inches = 0.3048 m
• 1 inch = 2.540 cm
• 1 nautical mile = 1852.2 m

Measures of weight

• 1 pood = 40 pounds = 16.380 kg
• 1 lb = 0.40951 kg

Main difference Metric from those that were used earlier is that it uses an ordered set of units of measure. This means that any physical quantity is characterized by a certain main unit, and all submultiples and multiples are formed according to a single standard, namely, using decimal prefixes.

The introduction of this systems of measures eliminates the inconvenience that was previously caused by the abundance of different units of measurement, which have rather complex rules for converting between themselves. Those in metric system are very simple and boil down to the fact that the original value is multiplied or divided by a power of 10.

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• International unit

Creation and development of the metric system of measures

The metric system of measures was created in late XVIII V. in France, when the development of trade industry urgently required the replacement of many units of length and mass, chosen arbitrarily, by single, unified units, which became the meter and kilogram.

Initially, the meter was defined as 1/40,000,000 of the Paris meridian, and the kilogram was defined as the mass of 1 cubic decimeter of water at a temperature of 4 C, i.e. the units were based on natural standards. This included one of key features metric system, which determined its progressive value. The second important advantage was the decimal subdivision of units, corresponding to the accepted system of calculation, and a single way of forming their names (by including the appropriate prefix in the name: kilo, hecto, deca, centi and milli), which eliminated complex conversions of one unit to another and eliminated confusion in titles.

The metric system of measures has become the basis for the unification of units throughout the world.

However, in subsequent years, the metric system of measures in its original form (m, kg, m, ml ar and six decimal prefixes) could not satisfy the demands of developing science and technology. Therefore, each branch of knowledge chose units and systems of units that were convenient for itself. So, in physics, the centimeter - gram - second (CGS) system was followed; in technology, a system with basic units has found wide distribution: meter - kilogram-force - second (MKGSS); in theoretical electrical engineering, several systems of units derived from the CGS system began to be used one after another; in heat engineering, systems were adopted based, on the one hand, on the centimeter, gram and second, on the other hand, on the meter, kilogram and second with the addition of a unit of temperature - degrees Celsius and off-system units of the amount of heat - calories, kilocalories, etc. . In addition, many other non-systemic units have found application: for example, units of work and energy - kilowatt-hour and liter-atmosphere, pressure units - millimeter of mercury, millimeter of water, bar, etc. As a result, a significant number of metric systems of units were formed, some of them covering certain relatively narrow branches of technology, and many non-systemic units, the definitions of which were based on metric units.

Their simultaneous application in certain areas led to the clogging of many calculation formulas with numerical coefficients that did not equal to one, which greatly complicates the calculations. For example, in engineering, it has become common to use kilograms to measure the mass of the ISS system unit, and kilogram-force to measure the force of the MKGSS system unit. This seemed convenient from the point of view that the numerical values ​​of the mass (in kilograms) and its weight, i.e. the forces of attraction to the Earth (in kilogram-forces) turned out to be equal (with an accuracy sufficient for most practical cases). However, the consequence of equating the values ​​of essentially heterogeneous quantities was the appearance in many formulas of the numerical coefficient 9.806 65 (rounded 9.81) and the confusion of the concepts of mass and weight, which gave rise to many misunderstandings and errors.

Such a variety of units and the associated inconveniences gave rise to the idea of ​​creating a universal system of units of physical quantities for all branches of science and technology, which could replace all existing systems and individual non-systemic units. As a result of the work of international metrological organizations, such a system was developed and received the name of the International System of Units with the abbreviation SI (International System). The SI was adopted by the XI General Conference on Weights and Measures (CGPM) in 1960 as modern form metric system.

Characteristics of the International System of Units

The universality of the SI is ensured by the fact that the seven basic units underlying it are units of physical quantities that reflect the basic properties of the material world and make it possible to form derived units for any physical quantities in all branches of science and technology. The same purpose is served by additional units necessary for the formation of derived units depending on the plane and solid angles. The advantage of the SI over other systems of units is the principle of constructing the system itself: the SI is built for a certain system of physical quantities that make it possible to represent physical phenomena in the form of mathematical equations; some of the physical quantities are taken as basic and through them all the rest are expressed - derived physical quantities. For the main quantities, units are established, the size of which is agreed upon at the international level, and for the remaining quantities, derived units are formed. The system of units constructed in this way and the units included in it are called coherent, since the condition is met that the ratios between the numerical values ​​of quantities expressed in SI units do not contain coefficients that are different from those included in the initially chosen equations connecting the quantities. The coherence of SI units in their application makes it possible to simplify calculation formulas to a minimum by freeing them from conversion factors.

The SI eliminated the plurality of units for expressing quantities of the same kind. So, for example, instead of a large number of pressure units used in practice, the SI unit of pressure is only one unit - the pascal.

The establishment of its own unit for each physical quantity made it possible to distinguish between the concepts of mass (SI unit - kilogram) and force (SI unit - Newton). The concept of mass should be used in all cases when we mean the property of a body or substance that characterizes their inertia and ability to create a gravitational field, the concept of weight - in cases where we mean the force arising from interaction with the gravitational field.

Definition of basic units. And it is possible with a high degree of accuracy, which ultimately not only improves the accuracy of measurements, but also ensures their unity. This is achieved by "materialization" of units in the form of standards and transfer from them to working measuring instruments with the help of a set of exemplary measuring instruments.

The international system of units, due to its advantages, has become widespread in the world. At present, it is difficult to name a country that would not implement the SI, would be at the stage of implementation or would not make a decision on the implementation of the SI. Thus, countries that previously used the English system of measures (England, Australia, Canada, the USA, etc.) also adopted the SI.

Consider the structure of the construction of the International System of Units. Table 1.1 shows the basic and additional SI units.

SI derived units are formed from basic and supplementary units. SI derived units with special names (Table 1.2) can also be used to form other SI derived units.

Due to the fact that the range of values ​​of most measured physical quantities can now be very significant and it is inconvenient to use only SI units, since the measurement results in too large or small numerical values, the SI provides for the use of decimal multiples and fractions of SI units , which are formed with the help of multipliers and prefixes given in Table 1.3.

International unit

On October 6, 1956, the International Committee of Weights and Measures considered the recommendation of the commission on the system of units and made the following important decision, completing the work on establishing the International System of Units of Measurement:

"The International Committee for Weights and Measures, Having regard to the task received from the Ninth General Conference on Weights and Measures in its Resolution 6, concerning the establishment of a practical system of units of measurement which could be adopted by all countries signatory to the Metric Convention; having regard to all documents , received from 21 countries responding to the survey proposed by the Ninth General Conference on Weights and Measures, taking into account Resolution 6 of the Ninth General Conference on Weights and Measures establishing the choice of base units for the future system, recommends:

1) to be called the "International System of Units" a system based on the base units adopted by the Tenth General Conference, which are as follows;

2) that the units of this system listed in the following table apply, without prejudice to other units that may be added subsequently."

At its session in 1958, the International Committee for Weights and Measures discussed and decided on a symbol for the abbreviation of the name "International System of Units". A symbol consisting of two letters SI (the initial letters of the words System International) was adopted.

In October 1958, the International Committee of Legal Metrology adopted the following resolution on the issue of the International System of Units:

metric system measure weight

"The International Committee of Legal Metrology, meeting in plenary session on October 7, 1958 in Paris, announces its accession to the resolution of the International Committee of Weights and Measures on the establishment of an international system of units of measurement (SI).

The main units of this system are:

meter - kilogram-second-ampere-degree Kelvin-candle.

In October 1960, the issue of the International System of Units was considered at the Eleventh General Conference on Weights and Measures.

On this issue, the conference adopted the following resolution:

"The Eleventh General Conference on Weights and Measures, Bearing in mind Resolution 6 of the Tenth General Conference on Weights and Measures, in which it adopted six units as the basis for the establishment of a practical system of measurement for international relations, Bearing in mind Resolution 3 adopted by the International Committee of Measures and weights in 1956, and taking into account the recommendations adopted by the International Committee of Weights and Measures in 1958, relating to the abbreviation of the name of the system and to prefixes for the formation of multiples and submultiples, decides:

1. Assign the name "International System of Units" to the system based on six basic units;

2. Set the international abbreviation for this system "SI";

3. Form the names of multiple and submultiple units using the following prefixes:

4. Use the following units in this system without prejudice to what other units may be added in the future:

The adoption of the International System of Units was an important progressive act that summed up a large long-term preparatory work in this direction and summarizing the experience of the scientific and technical circles of different countries and international organizations in metrology, standardization, physics and electrical engineering.

The decisions of the General Conference and the International Committee for Weights and Measures on the International System of Units are taken into account in the recommendations of the International Organization for Standardization (ISO) on units of measurement and are already reflected in the legislative provisions on units and in the unit standards of some countries.

In 1958, the GDR approved a new Regulation on units of measurement, built on the basis of the International System of Units.

In 1960, in the government regulation on the units of measurement of the Hungarian People's Republic based on the International System of Units.

State standards of the USSR for units 1955-1958. were built on the basis of the system of units adopted by the International Committee for Weights and Measures as the International System of Units.

In 1961, the Committee of Standards, Measures and Measuring Instruments under the Council of Ministers of the USSR approved GOST 9867 - 61 "International System of Units", which establishes the preferred use of this system in all areas of science and technology and in teaching.

In 1961, by government decree, the International System of Units was legalized in France and in 1962 in Czechoslovakia.

The international system of units was reflected in the recommendations of the International Union of Pure and Applied Physics, adopted by the International Electrotechnical Commission and a number of other international organizations.

In 1964, the International System of Units formed the basis of the "Table of Units of Legal Measurement" of the Democratic Republic of Vietnam.

Between 1962 and 1965 in a number of countries, laws have been issued to adopt the International System of Units as mandatory or preferred, and standards for SI units.

In 1965, in accordance with the instructions of the XII General Conference on Weights and Measures, the International Bureau of Weights and Measures conducted a survey on the status of the adoption of the SI in countries that had acceded to the Meter Convention.

13 countries have adopted the SI as mandatory or preferred.

In 10 countries, the use of the International System of Units has been admitted and preparations are underway to revise laws in order to give a legal, mandatory character to this system in this country.

In 7 countries, SI is admitted as optional.

At the end of 1962, a new recommendation of the International Commission on Radiological Units and Measurements (ICRU) was published, devoted to quantities and units in the field of ionizing radiation. Unlike the previous recommendations of this commission, which were mainly devoted to special (non-systemic) units for measuring ionizing radiation, the new recommendation includes a table in which the units of the International System are placed in the first place for all quantities.

At the seventh session of the International Committee of Legal Metrology, which took place on October 14-16, 1964, which included representatives of 34 countries that signed the intergovernmental convention establishing the International Organization of Legal Metrology, the following resolution was adopted on the implementation of the SI:

"The International Committee of Legal Metrology, taking into account the need for the rapid spread of the International System of Units of SI, recommends the preferred use of these SI units in all measurements and in all measuring laboratories.

In particular, in temporary international recommendations. accepted and widespread international conference legal metrology, these units should preferably be used for the calibration of measuring apparatus and instruments covered by these recommendations.

Other units permitted by these recommendations are only temporarily permitted and should be avoided as soon as possible."

The International Committee of Legal Metrology has established a rapporteur secretariat on Units of Measurement whose task is to develop a model draft legislation on units of measurement based on the International System of Units. Austria has taken over the rapporteur secretariat for this topic.

Benefits of the International System

The international system is universal. It covers all areas physical phenomena, all branches of technology and National economy. The international system of units organically includes such private systems that have long been widespread and deeply rooted in technology, such as the metric system of measures and the system of practical electrical and magnetic units (ampere, volt, weber, etc.). Only the system that included these units could claim recognition as universal and international.

The units of the International System are for the most part quite convenient in size, and the most important of them have practical names of their own.

The construction of the International System corresponds to the modern level of metrology. This includes the optimal choice of basic units, and in particular their number and size; consistency (coherence) of derived units; rationalized form of electromagnetism equations; the formation of multiples and submultiples by means of decimal prefixes.

As a result, various physical quantities in the International System, as a rule, have different dimensions. This makes a full-fledged dimensional analysis possible, preventing misunderstandings, for example, when checking calculations. Dimension indicators in SI are integer, not fractional, which simplifies the expression of derived units through basic ones and, in general, operating with dimensions. The coefficients 4n and 2n are present in those and only those equations of electromagnetism that relate to fields with spherical or cylindrical symmetry. The method of decimal prefixes, inherited from the metric system, makes it possible to cover huge ranges of changes in physical quantities and ensures that the SI complies with the decimal system.

The international system is inherently flexible. It allows the use of a certain number of non-systemic units.

SI is a living and developing system. The number of basic units can be further increased if necessary to cover any additional area of ​​phenomena. In the future, it is also possible that some of the regulatory rules in force in the SI will be relaxed.

The international system, as its very name says, is intended to become the only system of units of physical quantities universally used. The unification of units is a long overdue necessity. Already, the SI has made numerous systems of units unnecessary.

The international system of units is adopted by more than 130 countries around the world.

The International System of Units is recognized by many influential international organizations, including the United Nations Educational, Scientific and Cultural Organization (UNESCO). Among those who recognized the SI are the International Organization for Standardization (ISO), the International Organization of Legal Metrology (OIML), the International Electrotechnical Commission (IEC), the International Union of Pure and Applied Physics, etc.

Bibliography

1. Burdun, Vlasov A.D., Murin B.P. Units of physical quantities in science and technology, 1990

2. Ershov V.S. Implementation of the International System of Units, 1986.

3. Kamke D, Kremer K. Physical foundations units of measurement, 1980.

4. Novosiltsev. On the history of the basic SI units, 1975.

5. Chertov A.G. Physical quantities(Terminology, definitions, designations, dimensions), 1990.

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