In the Russian Federation, in accordance with the established procedure, units of quantities are allowed to be used international system units adopted by the General Conference on Weights and Measures recommended by the International Organization of Legal Metrology.
The names, designations and rules for writing units of quantities, as well as the rules for their application on the territory of the Russian Federation, are established by the Government of the Russian Federation, with the exception of cases provided for by legislative acts of the Russian Federation.
The Government of the Russian Federation may allow for use, along with units of quantities of the International System of Units, non-systemic units of quantities.
Characteristics and parameters of products supplied for export, including measuring instruments, can be expressed in units of quantities set by the customer.
3.1 State standards of units of quantities.
State standards of units of quantities are used as initial ones for reproducing and storing units of quantities in order to transfer their sizes to all means of measuring these quantities on the territory of the Russian Federation.
State standards of units of quantities are the exclusive federal property, are subject to approval by the State Standard of Russia and are under its jurisdiction.
3.2 Basic units.
Basic units of measurement of the International System of Units SI. There are seven in total:
The unit of length is the meter - the length of the path that light travels in vacuum in 1/299792458 of a second;
The unit of mass is kilogram - mass, equal to the mass international prototype of the kilogram
The unit of time is a second - the duration of 9192631770 periods of radiation corresponding to the transition between two levels of the hyperfine structure of the ground state of the cesium-133 atom in the absence of disturbance from external fields;
The unit of electric current strength - ampere - is the strength of an unchanging current, which, when passing through two parallel conductors of infinite length and negligible circular glow, located at a distance of 1 m from one another in a vacuum, would create a force between these conductors equal to 0.2 μN per each meter is long;
The unit of thermodynamic temperature is Kelvin - 1/273.16 part of the thermodynamic temperature of the triple point of water. Celsius scales are also allowed;
The unit of the amount of a substance is a mole - the amount of a substance of a system containing the same amount structural elements, how many atoms are contained in a carbon-12 nuclide with a mass of 0.012 kg;
The unit of luminous intensity is the candela - the luminous intensity in a given source direction, emitting monochromatic radiation with a frequency of 540 * THz, the energy strength of which in this direction is 1/683 W / sr ^ 2
3.3 Derived units.
Derived units can be expressed in terms of base units using the mathematical operations of multiplication and division. Some of the derived units, for convenience, have been assigned own names, such units can also be used in mathematical expressions to form other derived units. The mathematical expression for a derived unit of measure follows from the physical law by which this unit of measure is determined or the definition of the physical quantity for which it is introduced. For example, speed is the distance a body travels per unit time; respectively, the unit of speed is m/s (meter per second). Often the same unit can be written in different ways, using a different set of basic and derived units. However, in practice, established expressions are used that best reflect the physical meaning of the quantity.
Examples of non-system units:
Flat angle (radian), solid angle (steradian), Celsius temperature (degree Celsius), frequency (hertz), force (newton), energy (joule), power (watt), pressure (Pascal), luminous flux (lumen) ), illumination (lux), electric charge(coulomb), potential difference (volt), resistance (ohm), capacitance (farad), magnetic flux (Weber), magnetic induction (tesla), inductance (henry), electrical conductivity (Siemens), Radioactivity (Becquerel), absorbed dose ionizing radiation (Gray), effective dose of ionizing radiation (sievert), catalyst activity (catal).
Physical quantity called physical property material object, process, physical phenomenon, quantified.
The value of a physical quantity expressed by one or more numbers characterizing this physical quantity, indicating the unit of measurement.
The size of a physical quantity are the values of the numbers appearing in the meaning of the physical quantity.
Units of measurement of physical quantities.
The unit of measurement of a physical quantity is the fixed size value assigned to numerical value, equal to one. It is used for the quantitative expression of physical quantities homogeneous with it. A system of units of physical quantities is a set of basic and derived units based on a certain system of quantities.
Only a few systems of units have become widespread. In most cases, many countries use the metric system.
Basic units.
Measure physical quantity - means to compare it with another similar physical quantity, taken as a unit.
The length of an object is compared with a unit of length, body weight - with a unit of weight, etc. But if one researcher measures the length in sazhens, and another in feet, it will be difficult for them to compare these two values. Therefore, all physical quantities around the world are usually measured in the same units. In 1963, the International unit system SI (System international - SI).
For each physical quantity in the system of units, an appropriate unit of measurement must be provided. Standard units is its physical realization.
The length standard is meter- the distance between two strokes applied on a specially shaped rod made of an alloy of platinum and iridium.
Standard time is the duration of any correctly repeating process, which is chosen as the movement of the Earth around the Sun: the Earth makes one revolution per year. But the unit of time is not a year, but give me a sec.
For a unit speed take the speed of such a uniform rectilinear motion, at which the body moves 1 m in 1 s.
A separate unit of measurement is used for area, volume, length, etc. Each unit is determined when choosing one or another standard. But the system of units is much more convenient if only a few units are chosen as the main ones, and the rest are determined through the main ones. For example, if the unit of length is meter, then the unit of area is square meter, volume - cubic meter, speed - meter per second, etc.
Basic units The physical quantities in the International System of Units (SI) are: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd) and mole (mol).
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Basic SI units |
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Value |
Unit |
Designation |
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Name |
Russian |
international |
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The strength of the electric current |
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Thermodynamic temperature |
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The power of light |
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Amount of substance |
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There are also SI derived units that have own names:
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SI derived units with their own names |
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Unit |
Derived unit expression |
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Value |
Name |
Designation |
Via other SI units |
Through the main and additional units SI |
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Pressure |
m -1 ChkgChs -2 |
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Energy, work, amount of heat |
m 2 ChkgChs -2 |
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Power, energy flow |
m 2 ChkgChs -3 |
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Quantity of electricity, electric charge |
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electrical voltage, electric potential |
m 2 ChkgChs -3 CHA -1 |
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m -2 Chkg -1 Hs 4 CHA 2 |
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m 2 ChkgChs -3 CHA -2 |
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m -2 Chkg -1 Hs 3 CHA 2 |
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Flux of magnetic induction |
m 2 ChkgChs -2 CHA -1 |
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Magnetic induction |
kghs -2 CHA -1 |
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Inductance |
m 2 ChkgChs -2 CHA -2 |
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Light flow |
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illumination |
m 2 ChkdChsr |
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Activity radioactive source |
becquerel |
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Absorbed radiation dose |
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Andmeasurements. To obtain an accurate, objective and easily reproducible description of a physical quantity, measurements are used. Without measurements, a physical quantity cannot be quantified. Definitions such as "low" or "high" pressure, "low" or "high" temperature reflect only subjective opinions and do not contain comparisons with reference values. When measuring a physical quantity, it is assigned a certain numerical value.
Measurements are made using measuring instruments. There is quite a large number of measuring instruments and fixtures, from the simplest to the most complex. For example, length is measured with a ruler or tape measure, temperature with a thermometer, width with calipers.
Measuring instruments are classified: according to the method of presenting information (indicating or recording), according to the measurement method ( direct action and comparison), according to the form of presentation of indications (analogue and digital), etc.
The measuring instruments are characterized by the following parameters:
Measuring range- the range of values of the measured quantity, on which the device is designed during its normal operation (with a given measurement accuracy).
Sensitivity threshold- the minimum (threshold) value of the measured value, distinguished by the device.
Sensitivity- relates the value of the measured parameter and the corresponding change in instrument readings.
Accuracy- the ability of the device to indicate true value measured indicator.
Stability- the ability of the device to maintain given accuracy measurements within a certain time after calibration.
Unit of magnitude is a specific quantity, defined and accepted by agreement, with which other quantities of the same kind are compared.
Units of magnitude appeared when a person had a need to express something quantitatively. This “something” could be the number of objects, and then the measurement was simple and consisted in counting (the unit of magnitude is a piece). However, bulk substances (grain) and liquids did not lend themselves to piece counting. This is how volume measures arose, which became units of volume measurement. The first measures of length were parts of the human body (foot, step, elbow). The ways of forming measures and units of quantities in Russia are noted in the first section. In the English system of measures, there are still some units associated with the size of the human body. For example, foot (foot - foot) is average length human feet. The size of the foot equal to 30.48 cm was established as a result of averaging the size of the feet of people "leaving the temples from Sunday morning." The size of an inch (25.4 mm) originated as the length of three grains of barley, taken out from the middle part of the ear and attached to each other with their ends. So, by decision of King Edward II in 1324, the “legal inch” appeared. There are several versions regarding the origin of such a unit of length as the English yard (0.9144 m). This may be the distance from the tip of the nose of King Henry I to the end of the middle finger of his outstretched hand, and the length of the sword of this king. The mile (1.609 m) unit of length was created by averaging 1,000 human double steps. There are many such examples. The cubit is still a unit national measure lengths in Bulgaria.
The variety of units of measurement in the world has always made trading operations difficult, so everyone has strived for their unification. In the foreseeable historical period, the process of unification of units of quantities went through at least three stages.
At the first stage, the size of a unit of magnitude was equated to the size of a magnitude reproduced by a natural measure, for example, to a cubit.
At the second stage, units of quantities were fixed in “real samples”, standards of length and mass were created - a meter and a kilogram.
At the third stage, for a more accurate and reliable reproduction of a number of quantities, units of quantities were torn off from the "measure", from quantitative characteristics properties of physical objects intended for their reproduction. For example, a meter remains a meter, but its length is measured by the length of the path that light travels in vacuum in 1/299792458 of a second.
Apparently, the process of refining the sizes of units will continue, since it has certainly become clear that human-made material (objective) standards of units of magnitude cannot ensure the storage and transmission of their size with the required accuracy.
Any measurement associated with finding numerical values physical quantities, with the help of them, the patterns of the phenomena that are being studied are determined.
concept physical quantities, for example, forces, weights, etc., is a reflection of the objectively existing characteristics of inertia, extension, and so on, inherent in material objects. These characteristics exist outside and independently of our consciousness, regardless of the person, the quality of the means and methods that are used in the measurements.
Physical quantities that characterize a material object under given conditions are not created by measurements, but are only determined using them. measure any value it means to define it numerical ratio with some other homogeneous quantity, which is taken as a unit of measurement.
Based on this, measurement called the comparison process. set value with some of its value, which is taken as unit of measure.
Relationship formula between the quantity for which the derived unit is established and the quantities A, B, C, ... units they are installed independently, general view:
where k- numerical coefficient (in given case k=1).
The formula for relating a derived unit to base or other units is called formuladimensions, and the exponents dimensions For convenience when practical use units introduced such concepts as multiples and submultiples.
Multiple unit- a unit that is an integer number of times greater than a system or non-system unit. A multiple unit is formed by multiplying the basic or derived unit by the number 10 to the appropriate positive power.
submultiple unit - a unit that is an integer number of times less than a system or non-system unit. The submultiple unit is formed by multiplying the basic or derived unit by the number 10 to the appropriate negative power.
Definition of the term “unit of measure“.
Unification of the unit of measurement engaged in a science called metrology. AT exact translation is the science of measurement.
Looking into International Dictionary metrology, we find that unit- it is valid scalar, which is defined and accepted by agreement, with which it is easy to compare any other quantity of the same kind and express their ratio using a number.
A unit of measurement can also be considered as a physical quantity. However, between a physical quantity and a unit of measurement there is a very important difference: The unit of measure has a fixed, conventionally accepted numerical value. This means that the units of measurement for the same physical quantity may be different.
For example, weight can have the following units: kilogram, gram, pound, pood, centner. The difference between them is clear to everyone.
The numerical value of a physical quantity is represented by the ratio of the measured value to standard value, which is unit of measure. A number that has a unit of measure named number.
There are basic and derived units.
Basic units set for such physical quantities that are selected as the main ones in a particular system of physical quantities.
Thus, the International System of Units (SI) is based on the International System of Units, in which the main quantities are seven quantities: length, mass, time, electricity, thermodynamic temperature, amount of substance and luminous intensity. So, in SI, the base units are the units of quantities that are indicated above.
The size basic units set by agreement within a specific system of units and fixed either with the help of standards (prototypes), or by fixing the numerical values of fundamental physical constants.
Derived units determine through the main method of using those connections between physical quantities, which are set in the system of physical quantities.
There are a huge number different systems units. They differ both in the systems of quantities on which they are based and in the choice of base units.
Usually, the state, through laws, establishes a certain system of units that is preferred or mandatory for use in the country. In the Russian Federation, the units of quantities of the SI system are the main ones.
Systems of units of measure.
Metric systems.
- ICSS,
Systems of natural units of measurement.
- atomic system of units,
- planck units,
- Geometric system of units,
- Lorentz-Heaviside units.
Traditional systems of measures.
- Russian system of measures,
- English system measures
- French system measures
- Chinese system measures
- Japanese system measures
- Already obsolete (ancient Greek, ancient Roman, ancient Egyptian, ancient Babylonian, ancient Hebrew).
Units of measurement grouped by physical quantities.
- Mass units (mass),
- Temperature units (temperature),
- Distance units (distance),
- Area units (area),
- Volume units (volume),
- Units of measurement of information (information),
- Time units (time),
- Pressure units (pressure),
- Heat flux units (heat flux).
Fixed size, which is conditionally assigned a numerical value equal to 1 (\displaystyle 1). Any other quantity of the same kind can be compared with the unit of a physical quantity and their ratio can be expressed as a number. It is used for the quantitative expression of physical quantities homogeneous with it. Units of measurement have names and designations assigned to them by agreement.
A number with an indication of the unit of measure is called named.
Distinguish between basic and derived units. The basic units in this system of units are established for those physical quantities that are chosen as the main ones in the corresponding system of physical quantities. So, the International System of Units (SI) is based on the International System of Units (eng. International System of Quantities, ISQ), in which the main ones are seven quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance and luminous intensity. Accordingly, in SI, the basic units are the units of the indicated quantities.
The sizes of the basic units are established by agreement within the framework of the corresponding system of units and are fixed either with the help of standards (prototypes) or by fixing the numerical values of the fundamental physical constants.
Derived units are determined through the main ones by using those relationships between physical quantities that are established in the system of physical quantities.
There is a large number various systems units that differ both in the systems of quantities on which they are based and in the choice of base units.
The rules for writing unit designations in the production of scientific literature, textbooks and other printed products are defined by GOST 8.417-2002 "State system for ensuring the uniformity of measurements". In printed publications, it is allowed to use either international or Russian designations of units. The simultaneous use of both types of designations in the same publication is not allowed, with the exception of publications on units of physical quantities.
Story
Units of measurement were among the earliest tools invented by humans. primitive societies needed elementary measures to solve everyday problems: building dwellings of a certain size and shape, creating clothes, exchanging food or raw materials.
The earliest known unified measurement systems appear to have been created in the 4th and 3rd millennia BC. e. the ancient peoples of Mesopotamia, Egypt, the Indus Valley, and possibly also Persia.
There are mentions of weight and measure in the Bible (Leviticus 19:35-36) - this is a commandment to be honest and have fair measures.
In 1875, an agreement on the Meter Convention was signed between 17 countries. With the signing of this treaty, the International Bureau of Weights and Measures and the International Committee of Weights and Measures were established and the General Conferences on Weights and Measures (CGPM) were established, usually meeting every four years. These international bodies created the current SI system, which was adopted in 1954 by the 10th CGPM and approved by the 11th CGPM in 1960.
On November 16, 2018, the session of the 26th CGPM was held in Versailles at the Palace of Congress, which fixed the new definitions of four of the seven basic units of the International System of Units SI (kilogram, ampere, kelvin and mole) and put an end to the dependence of the SI on a specific material object - the international platinum iridium prototype of the kilogram (since 1889), which will be officially replaced new implementation as physical experiment value based
