Measurements, quantities and units
The SI system, standards and dimensions, measuring instruments and the accuracy of measurements.
Material on this topic
Units of physical quantities 1 Å = 10 -10 m = 10 -8 cm = 10 -4 µm = 10 -1 nm 1 rad = 57°17`44.8`` = 53.3° = 3.44·10 3 ` = 2.06·10 5 `` 1 g/cm 3 = 10 3 kg/cm 3 = 1 t/m 3 1 dyn = 10 -5 N = 1.02·10 -9 kgf 1 atm = 1.01·10 5 …
1 mile = 7 versts = 7.4676 km 1 verst = 500 sazhens = 1.0668 km 1 sazhen = 3 arshins = 7 feet = 2.1336 m 1 arshin = 16 vershoks = 28 inches = 0.7112 m 1 vershok = 1.75 inches = 44.45 mm 1 foot = 12 inches = 0.3048 m 1 in…
Desyatina, economic (a measure of land area).
Mechanical quantities Name Symbol Weight G, P, W Time t Height h Pressure p Diameter d Length l Path length s Amount of substance ν, n Momentum p Stiffness coefficient k Safety factor k, n Efficiency η Coefficient of rol…
Acoustic quantities Name Symbol Wavelength λ Sound power P Sound energy W Sound intensity I Speed of sound c Frequency ν, f
Thermal quantities and quantities of molecular physics Name Symbol Absolute humidity a Gas constant (molar) R Quantity of heat Q Efficiency η Relative humidity φ Relative molecular mass M r Avogadro constant (number) N A…
Units of time s Ms d h min µs ns 1 s 1 10 -6 1.16·10 -5 2.78·10 -4 1.67·10 -2 10 6 10 9 1 Ms 10 6 1 11.6 278 1.67·10 4 10 12 10 15 1 d 86 400 8.64·10 -2 1 24 1440 8.64·10 10 8.64·10 13 1 h 3 600 3.6·10 -3 0.04167 1 60 3.…
Units of length m km cm mm μm nm 1 m 1 10 -3 100 10 3 10 6 10 9 1 km 10 3 1 10 5 10 6 10 9 10 12 1 cm 0.01 10 -5 1 10 10 4 10 7 1 mm 10 -3 10 -6 0.1 1 10 3 10 6 1 μm 10 -6 10 -9 10 -4 10 -3 1 10 3 1 nm 10 -9 10 -12 10 -7…
Electrical and magnetic quantities Name Symbol Permittivity of vacuum (electric constant) ε 0 Inductance L Coefficient of self-induction L Transformation ratio n Magnetic induction B Permeability of vacuum (magnetic cons…
Units of mass kg Mt t q g mg u 1 kg 1 10 -9 10 -3 0.01 10 3 10 6 6.02·10 26 1 Mt 10 9 1 10 6 10 7 10 12 10 15 6.02·10 35 1 t 10 3 10 -6 1 10 10 6 10 9 6.02·10 29 1 q 100 10 -7 0.1 1 10 5 10 8 6.02·10 28 1 g 10 -3 10 -12 …
Units of velocity m/s km/s cm/s m/min km/h kn 1 m/s 1 10 -3 100 60 3.6 1.94 1 km/s 10 3 1 10 -5 6·10 4 3600 1940 1 cm/s 0.01 10 5 1 0.6 0.036 1.94·10 -2 1 m/min 1.67·10 -2 1.67·10 -5 1.67 1 0.06 3.24·10 -2 1 km/h 0.278 2…
Units of power W kW MW kgf·m/s erg/s hp 1 W 1 10 -3 10 -6 0.102 10 7 1.36·10 -3 1 kW 10 3 1 10 -3 10 2 10 10 1.36 1 MW 10 6 10 3 1 1.02·10 5 10 13 1.36·10 3 1 kgf·m/s 9.81 9.81·10 -3 9.81·10 -6 1 9.81·10 7 1.33·10 -2 1 e…
Optical quantities Name Symbol Wavelength λ Illuminance E Period of oscillation T Refractive index (refraction coefficient) n Luminous flux Ф Aperture ratio of a lens f Luminous intensity I Speed of light c Linear magnif…
Quantities of atomic physics Name Symbol Relative atomic mass A r Half-life T 1/2 Mass defect Δ Charge of the electron e Mass of an atom m a Mass of the neutron m n Mass of the proton m p Mass of the electron m e Planck …
Unit Name Symbol Russian International Ångström Å Å Are а а Astronomical unit а. е. ua Atomic mass unit а. е. м. u Technical atmosphere ат at Physical (standard) atmosphere атм atm Bar бар bar Watt Вт W Hectare га ha Hec…
Unit Name Symbol Russian International Degree Celsius °С °С Gigajoule ГДж GJ Joule Дж J Joule per kilogram Дж/кг J/kg Joule per kilogram-kelvin Дж/(кг·К) J/(kg·K) Calorie кал cal Calorie per gram кал/г cal/g Calorie per …
The first prefixes in physics were introduced in 1793—1795, when the metric system of measures was legalised in France.
Unit Name Symbol Russian International Ampere А A Ampere-second А·с A·s Watt Вт W Watt-hour Вт·ч W·h Weber Вб Wb Volt В V Gauss Гс Gs Henry Гн H Hertz Гц Hz Gigawatt ГВт GW Joule Дж J Kilowatt кВт kW Kilowatt-hour кВт·ч …
Unit Name Symbol Russian International Dioptre дптр - Candela кд cd Lux лк lx Lumen лм lm
Units of length Point 0.254 mm Line 2.54 mm Inch 25.4 mm Vershok 44.4 mm Foot 304.8 mm Arshin ≈ 71.1 cm Sazhen ≈ 213.4 cm Verst = 500 sazhens = = 1500 arshins= =1066.8 m ≈ 1.07 km Units of area Square line ≈ 6.45 mm 2 Sq…