On 27 february 1984, the state council, in issuing the order on the unified application of statutory measures in our country, stated that all units of measurement in our country are governed by the statutory unit of measurement of the people's republic of china. Our statutory units of measurement are based on the international system of units (si) and include non-international units selected by 10 of our countries, such as time (minutes, hours, days), azimuth (seconds, minutes, degrees), length (sea), mass (tons) and volume (lifts), etc. In the international unit system, it is divided into basic, export and support units. The basic units are those of physics that can be defined independently of each other and are seven units of mass (m), time unit seconds (s), mass unit kg (kg), electrical unit amber (a), thermodynamic temperature unit kelvin (k), light strength unit candra (cd) and mass unit mol. Units derived from basic units by definition, law and other functional relationships are referred to as export units, e. G. Newton (n) of force is defined as “the power of an object having an acceleration of 1 kg per second of 1 metre”, i. E. 1n = 1kg m/s2. In electrons, the units of other physical quantities, except currents, are the units of export, e. G. The frequency is hz, defined as the “frequency of periodic phenomena with a cycle of one second”, i. E. 1 hz = 1/s. At the international level, units that can be both basic and export units are called support units. The international unit system includes two auxiliary units, the radians (rad) of square angles and the unit arcs (sr) of stereo angles。
