en:measurement
Table of Contents
Measurement
SI: Système International (SI) d’unités; International system of units.
SI base units
SI derived units
| Quantity | Name of unit | Symbol | Equivalent units |
|---|---|---|---|
| Area | square meter | m$^2$ | |
| Volume | cubic meter | m$^3$ | |
| Frequency | hertz | Hz | s$^{-1}$ |
| Density, mass density | kilogram per cubic meter | kg m$^{-3}$ | |
| Speed, velocity | meter per second | m s$^{-1}$ | |
| Angular speed, angular velocity | radian per second | rad s$^{-1}$ | |
| Acceleration | meter per second squared | m s$^{-2}$ | |
| Angular acceleration | radian per second squared | rad s$^{-2}$ | |
| Force | newton | N | kg m s$^{-2}$ |
| Pressure, mechanical stress | pascal | Pa | N m$^{-2}$ |
| Kinematic viscosity | square meter per second | m$^2$ s$^{-1}$ | |
| Dynamic viscosity | newton-second per meter squared | N s m$^{-2}$ | |
| Work, energy, quantity of heat | joule | J | N m |
| Power | watt | W | J s$^{-1}$ |
| Charge, quantity of electricity | coulomb | C | A s |
| Potential difference, electromotive force | volt | V | J C$^{-1}$, W A$^{-1}$ |
| Electric field strength | volt per meter | V m$^{-1}$ | N C$^{-1}$ |
| Electric resistance | ohm | $\Omega$ | V A$^{-1}$ |
| Capacitance | farad | F | A s V$^{-1}$ |
| Magnetic flux | weber | Wb | V s |
| Inductance | henry | H | V s A$^{-1}$ |
| Magnetic flux density | tesla | T | Wb m$^{-2}$ |
| Magnetic field strength | ampere per meter | A m$^{-1}$ | |
| Magnetomotive force | ampere | A | |
| Luminous flux | lumen | lm | cd sr |
| Luminance | candela per square meter | cd m$^{-2}$ | |
| Illuminance | lux | lx | lm m$^{-2}$ |
| Wave number | one per meter | m$^{-1}$ | |
| Entropy | joule per kelvin | J K$^{-1}$ | |
| Specific heat capacity | joule per kilogram-kelvin | J kg$^{-1}$ K$^{-1}$ | |
| Thermal conductivity | watt per meter-kelvin | W $m^{-1}$ K$^{-1}$ | |
| Radiant intensity | watt per steradian | W sr$^{-1}$ | |
| Activity, radioactivity | becquerel | Bq | s$^{-1}$ |
| Radiation dose | gray | Gy | J kg$^{-1}$ |
| radiation dose equivalent | sievert | Sv | J kg$^{-1}$ |
| Angle (plane) | radian | rad | |
| Solid angle | steradian | sr |
Unit prefixes
| Prefix | Base 10 | English word | ||
|---|---|---|---|---|
| Name | Symbol | Short scale | Long scale | |
| yotta | Y | $10^{24}$ | septillion | quadrillion |
| zetta | Z | $10^{21}$ | sextillion | trilliard |
| exa | E | $10^{18}$ | quintillion | trillion |
| peta | P | $10^{15}$ | quadrillion | billiard |
| tera | T | $10^{12}$ | trillion | billion |
| giga | G | $10^9$ | billion | milliard |
| mega | M | $10^6$ | million | |
| kilo | k | $10^3$ | thousand | |
| hecto | h | $10^2$ | hundred | |
| deca | da | $10^1$ | ten | |
| $10^0$ | one | |||
| deci | d | $10^{-1}$ | tenth | |
| centi | c | $10^{-2}$ | hundredth | |
| milli | m | $10^{-3}$ | thousandth | |
| micro | μ | $10^{-6}$ | millionth | |
| nano | n | $10^{-9}$ | billionth | milliardth |
| pico | p | $10^{-12}$ | trillionth | billionth |
| femto | f | $10^{-15}$ | quadrillionth | billiardth |
| atto | a | $10^{-18}$ | quintillionth | trillionth |
| zepto | z | $10^{-21}$ | sextillionth | trilliardth |
| yocto | y | $10^{-24}$ | septillionth | quadrillionth |
Length-scales in the universe
Numerical constants
Fundamental physical constants
| Name | Symbol | Python code scipy.constants. | Value |
|---|---|---|---|
| Speed of light in vacuum | c | c | $3.0 \times 10^8$ m s$^{-1}$ |
| Magnitude of charge of electron | e | e | $1.6\times 10^{-19}$ C |
| Gravitational constant | G | G | $6.7\times 10^{-11}$ N m$^2$ kg$^{-2}$ |
| Planck’s constant | h | h | $6.6\times 10^{-34}$ J s |
| Boltzmann constant | k | k | $1.4\times 10^{-23}$ J K$^{-1}$ |
| Avogadro’s number | N$_A$ | N_A | $6.0\times 10^{23}$ mol$^{-1}$ |
| Gas constant | R | R | $8.3$ J mol$^{-1}$ K$^{-1}$ |
| Mass of electron | m$_e$ | m_e | $9.1\times 10^{-31}$ kg |
| Mass of proton | m$_p$ | m_p | $1.7\times 10^{-27}$ kg |
| Mass of neutron | m$_n$ | m_n | $1.7\times 10^{-27}$ kg |
| Permeability of free space | $\mu_0$ | mu_0 | $1.3 \times 10^{-6}$ T m A$^{-1}$ |
| Permittivity of free space | $\epsilon_0$ | epsilon_0 | $8.9\times 10^{-12}$ C$^2$ N$^{-1}$ m$^{-2}$ |
Astronomical data
| Name | Symbol | Python code |
|---|---|---|
| Hubble constant | ||
| Age of the universe | ||
| 1 astronomical unit (AU) |
en/measurement.txt · Last modified: by 127.0.0.1