ISO/IEC 80000, Quantities and units, is an international standard describing the International System of Quantities (ISQ). It was developed and promulgated jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It serves as a style guide for using physical quantities and units of measurement, formulas involving them, and their corresponding units, in scientific and educational documents for worldwide use. The ISO/IEC 80000 family of standards was completed with the publication of the first edition of Part 1 in November 2009.
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In this Dossier
ISO/IEC 80000 in the context of Spherical coordinate system
In mathematics, a spherical coordinate system specifies a given point in three-dimensional space by using a distance and two angles as its three coordinates. These are
- the radial distance r along the line connecting the point to a fixed point called the origin;
- the polar angle θ between this radial line and a given polar axis; and
- the azimuthal angle φ, which is the angle of rotation of the radial line around the polar axis.
(See graphic regarding the "physics convention".)
ISO/IEC 80000 in the context of Base quantity
The International System of Quantities (ISQ) is a standard system of quantities used in physics and in modern science in general. It includes seven ISQ base quantities – length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity – and the relationships between those quantities in derived quantities. This system underlies the International System of Units (SI) but does not itself determine the units of measurement used for the quantities.The system is formally described in a multi-part standard ISO/IEC 80000, which also defines many other derived quantities used in science and technology, first completed in 2009 and subsequently revised and expanded.
ISO/IEC 80000 in the context of Metric prefix
Decimal multiplicative prefixes have been a feature of all forms of the metric system, with six of these dating back to the system's introduction in the 1790s. Metric prefixes have also been used with some non-metric units. The SI prefixes are metric prefixes that were standardised for use in the International System of Units (SI) by the International Bureau of Weights and Measures (BIPM) in resolutions dating from 1960 to 2022. Since 2009, they have formed part of the ISO/IEC 80000 standard. They are also used in the Unified Code for Units of Measure (UCUM).
ISO/IEC 80000 in the context of Standard gravity
The standard acceleration of gravity or standard acceleration of free fall, often called simply standard gravity, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is a constant defined by standard as 9.80665 m/s (about 32.17405 ft/s), denoted typically by ɡ0 (sometimes also ɡn, ɡe, or simply ɡ). This value was established by the third General Conference on Weights and Measures (1901, CR 70) and used to define the standard weight of an object as the product of its mass and this nominal acceleration. The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from the rotation of the Earth (but the latter is small enough to be negligible for most purposes); the total (the apparent gravity) is about 0.5% greater at the poles than at the Equator.
Although the symbol ɡ is sometimes used for standard gravity, ɡ (without a suffix) can also mean the local acceleration due to local gravity and centrifugal acceleration, which varies depending on one's position on Earth (see Earth's gravity). The symbol ɡ should not be confused with G, the gravitational constant, or g, the symbol for gram. The ɡ is also used as a unit for any form of acceleration, with the value defined as above ().