Physical Constants

pyunitx.constants.G = 6.67430E-11 m^3 kg^-1 s^-2

Newton’s gravitational constant G shows up in the classical equation F = \frac{GMm}{r^2}. It is given here in \frac{m^3}{kg s^2}.

pyunitx.constants.M_E = 5.9722E+24 kg

The earth’s total mass. Its value is retrieved from here. It is given in kg.

pyunitx.constants.M_air = 0.0289647 kg mol^-1

The average molar mass of dry air means the mass of one mole of air. Factoring in molar mass means you can transform the ideal gas law into PV = \frac{m}{M_{air}} R T if you have a mass instead of molarity which is the common case. It is in units of \frac{kg}{mol}

pyunitx.constants.N_A = Decimal('6.02214076E+23')

Avogadro’s number is the number of molecules making up one mole, approximately 6.022\times 10^{23}

pyunitx.constants.R = 8.31446261815324 m^2 kg K^-1 mol^-1 s^-2

The ideal gas constant relates the pressure, volume, quantity, and temperature of a gas to each other. This equation is PV = nRT. It is given in \frac{J}{mol K}.

pyunitx.constants.R_E = 6378137 m

The earth’s equatorial radius, as measured for the WGS 84 ellipsoid. Its value is retrieved from here. It is given in m.

pyunitx.constants.atm = 101325 Pa

One standard atmosphere is approximately the average sea-level atmospheric pressure. It is given in Pa.

pyunitx.constants.c = 299792458 m s^-1

The speed of light in a vacuum c is an absolute constant of the universe. It now forms the foundation for the definition of the meter. It is given here in \frac{m}{s}.

pyunitx.constants.g = 9.80665 m s^-2

Standard earth’s gravity is an average of measurements taken around the world. If you live at a high elevation, you may measure a lower acceleration because you are further from the center of the earth. It is in units of \frac{m}{s^2}

pyunitx.constants.σ = 5.670374419E-8 kg s^-3 K^-4

The Stefan-Boltzmann constant relates the temperature of an object to how much electromagnetic radiation it emits. It appears in the equation j^* = \sigma T^4. It is given in units of \frac{W}{m^2 K^4}.