In [1]:
# distance
ft_per_mile = 5280 # 5280 ft = 1 mile (exact)
cm_per_in = 2.54 # 2.54 cm = 1 in (exact)
in_per_cm = 1/cm_per_in
mile_per_ft = 1/ft_per_mile
m_per_mile = ft_per_mile * 12 * cm_per_in / 100
mile_per_m = 1/m_per_mile
# angle
pi = 3.141592653589793
deg_per_rad = 180/pi # 360 deg = 2pi rad
rad_per_deg = 1/deg_per_rad
# force
N_per_lb = 4.448 # 1 lb = 4.448 N
lb_per_N = 1/N_per_lb
# mass
kg_per_amu = 1.66054e-27 # 1 amu = 1.66054x10^-27 kg
kg_per_slug = 14.59 # 14.49 kg = 1 slug
slug_per_kg = 1/kg_per_slug
amu_per_kg = 1/kg_per_amu
# pressure
Pa_per_psi = in_per_cm**2*100**2*N_per_lb
psi_per_Pa = 1/Pa_per_psi
In [2]:
g = 9.8 # N/kg (or m/s^2) Grav. field strength at the Earth's surface
G = 6.67e-11 # N.m^2/kg^2 universal gravity constant
I0 = 1e-12 # W/m^2 hearing threshold intensity
p0 = 101.3e3 # Pa standard atmospheric pressure
ME = 5.98e24 # kg mass of the Earth
RE = 6.37e6 # m mean radius of the Earth
astronomical data¶
In [3]:
M_earth = 5.97e24 # kg mass of earth
M_sun = 333000*M_earth # kg mass of sun
M_moon = 7.36e22 # kg mass of moon
R_earth_orbit = 149.6e9 # m radius of earth's orbit (1 AU)
R_moon_orbit = 3.86e8 # m radius of Moon's orbit
For more, see textbook Appendix D.
Physics 2¶
In [4]:
# thermodynamics
T_zero = 273.15 # deg C Celsius offset from absolute zero
kB = 1.38e-23 # J/K Boltzmann constant
NA = 6.02e23 # particles/mol Avogadro's number
RR = NA*kB # J/mol.K Gas constant
sigma_ = 5.67e-8 # W/m^2.K^4 Stefan-Boltzmann constant
# Electricity and Magnetism
epsilon0 = 8.85419e-12 # mks units permittivity of free space
ke = 1/(4*pi*epsilon0) # mks units Coulomb constant
mu0 = pi*4e-7 # mks units permeability of free space
qe = 1.6e-19 # C fundamental charge
me = 9.109e-31 # kg mass of electron
mp = 1.672621e-27 # kg mass of proton
Official Data¶
2022 Reference on Constants, Units and Uncertainty
Data provided by the Physical Measurement Laboratory of the US National Institute of Standards and Technology. These numbers are recommended by the Committee on Data of the International Science Council (CODATA).
These data are conveniently collected in
scipy.constants.
For example:
import scipy.constants
amu,unit,unc = scipy.constants.physical_constants['atomic mass constant']
print(f'1 amu = {amu} ± {unc} {unit}')
1 amu = 1.6605390666e-27 ± 5e-37 kg