Measurements, quantities and units

1 nm 10 -3 1 10 10 3 10 4 10 6 1 A * 10 -4 10 -1 1 10 2 10 3 10 5 1 pm 10 -6 10 -3 10 -2 1 10 10 3 1 X-unit 10 -7 10 -4 10 -3 10 -1 1 10 2 1 fm ** 10 -9 10 -6 10 -5 10 -3 10 -2 1 * In honour of the Swedish physicist A.

The following units of length are often used to measure large distances (for example, in astronomy and astronautics): the astronomical unit, the light year and the parsec.

Units of length Mile ≈ 1.609 km Nautical mile 1.852 km (exact) Cable 185.2 m (exact) Yard 914.4 mm (exact) Foot 304.8 mm (exact) Inch 25.4 mm (exact) Large line 2.54 mm (exact) Small line ≈ 2.12 mm Units of area Acre ≈ 4…

The PQR system is a multi-level (multi-layered) dimensional construction made up of physical quantities (PQ), the elements of the system.

Geiger-Müller counters help to monitor ionising radiation today.

V.M.Yurovitsky, Moscow Humanity's entry into space compels a fresh interpretation of many mechanical concepts.

the ohm, the volt, the ampere and others, established for practical electrical measurements by the 1st International Congress of Electricians (1881).

contain a limited number of base units of physical quantities, the remaining units of the system being defined as derived from the base ones.

(Avogadro's number) - the number of structural elements (atoms, molecules, ions or other particles) in 1 mole.

Autocollimator , an optico-mechanical instrument for precise angular measurements.

Bar (from the Greek baros — weight) (bar). 1) a unit of pressure outside any system of units; 1 bar = 10 5 Pa = 10 6 dyn/cm 2 = 0.986923 atm; 1 mbar=10 3 dyn/cm 2 =0.986923•10 -3 atm = 0.75 mm Hg. 2) An obsolete name for…

Barn (English barn) (b), a unit of area used to express the effective cross section of nuclear processes; 1 b = 10 -24 cm 2 =10 -28 m 2.

Becquerel (Bq), the SI unit of the activity of a nuclide in a radioactive source (the activity of an isotope); 1 Bq is the activity of a nuclide at which one decay event occurs in 1 s.

Bel (B), the SI unit of a logarithmic relative quantity (the decimal logarithm of the ratio of the values of two physical quantities of the same kind).

Bernoulli equation (the Bernoulli integral) in hydroaeromechanics [[after the Swiss scientist D.

Bit (bit) (from the English binary — twofold, and digit — sign, figure), the unit of quantity of information in the binary system.

Brownian motion , (Braunian motion), the disorderly motion of small particles suspended in a liquid or a gas, which takes place under the impacts of the molecules of the surrounding medium.

Rem (ber, rem), a non-SI unit of the equivalent dose of ionising radiation. 1 rem = 0.01 J/kg.

Galvanometer, an electrical measuring instrument of high sensitivity for measuring small currents, voltages and quantities of electricity (see Ballistic galvanometer ).

(from the Greek hekaton - a hundred), a prefix added to the name of a unit of a physical quantity to form the name of a multiple unit equal to 100 of the original units.