Physical Constants

Acceleration Due to Gravity

\(g = 9.806 65 E+00 \frac{m}{s^2}= 3.217 405 E+01 \frac{ft}{s^2}\)

Alpha Particle Rest Mass

\(m_{\alpha} = 6.644 656 20(33) E-27 kg = 4.001 506 179 127(62) E+00u\)

Alpha Particle Rest Mass Equivalent Energy

\(m_{\alpha} c^2 = 3.727 379 109(93) E+03 MeV\)

Atomic Mass Unit = (\(\frac{10^{-3} \frac{kg}{mol}}{N_A}\))

u = 1.660 538 782(83) E-27 kg

Atomic Mass Unit-Electron Volt Relationship

1 uc² = 9.314 940 28(23) E+02 MeV

Avogadro Constant (entities per mole)

N_A = 6.022 141 79(30) E+23

Bohr Magneton = \(\frac{e \hbar}{2m_e}\)

\(\mu_B = 9.274 009 15(23) E-24 \frac{J}{T}\)

Bohr Radius

\(\alpha _o 5.291 772 106 E-11 m \)

Boltzmann Constant = \(\frac{R}{N_A}\)

\( k = 1.380 650 4(24) E-24 \frac{J}{K} = 8.613 43(15) E-05 \frac{eV}{K} \)

Characteristic Impedance of Vacuum = \((\frac{\mu_0}{\epsilon_0})^{\frac{1}{2}}\)

\(Z_0\) = 3.767 303 134 61 E+02 Ohms

Classical Electron Radium = \(\alpha^{2}\alpha_0\)

\(r_e\) = 2.817 940 289 4(58) E-15 meters

Deuteron Rest Mass

\(m_d\) = 3.343 583 20(17) E-27 kg = 2.013 553 212 724(78) E+00 u

Deuteron Rest Mass Equivalent Energy

\(m_d c^2\) = 1.875 612 793(47) E+03 MeV

Electron Charge to Mass Ratio

\(\frac{-e}{m_e} = -1.758 820 150(44) E+11 \frac{C}{kg}\)

Electron Rest Mass

\(m_e = 9.109 382 15(45) E-31 kg = 5.485 799 0943(23) E-04 u\)

Electron Rest Mass Equivalent Energy

\(m_e c^2 = 5.109 989 10(13) E-01 MeV \)

Elementary Charge

e = 1.602 176 487(40) E-19 coulomb

Faraday Constant

\( F = 9.648 533 99(24) E+04 \frac{C}{mole}\)

Fine-structure constant

\( \alpha \) = 7.297 352 5376(50) E-03 (dimensionless)

Gravitational Constant

\( G = 6.674 28(67) E-11 \frac{N \ m^2}{kg^2} \)

Molar Gas Constant

\(R = 8.314 472(15) E+00 \frac{J}{mole \ kelvin}\)

Molar Mass Constant

\(M_u = 1 E-3 \frac{kg}{mol}\)

Neutron Rest Mass

\( m_n = 1.674 927 211(84) E-27 kg = 1.008 664 915 97(43) E+00 u \)

Neutron Rest Mass Equivalent Energy

\(m_n c^2 = 9.395 653 46(23) E+02 MeV \)

Permittivity of Free Space (Electric Constant) = \(\frac{1}{\mu_0 c^2}\)

\(\epsilon_0 = 8.854 187 817 E-12 \frac{C^2}{J \ m} = 8.854 187 871 E-12 \frac{F}{m}\)

Planck Constant

h = 6.626 068 96(33) E-34 Js = 4.135 667 33(10) E-21 MeV second

Proton mass to electron mass ratio

\(\frac{m_p}{m_e} = 1.836 152 672 47(80) E+03 \)

Proton Rest Mass

\(m_p = 1.672 621 637 E-27 kg = 1.007 276 466 77(10) E+00 u \)

Proton Rest Mass Equivalent Energy

\(m_p c^2 = 9.382 720 13(23) E+02 MeV\)

Speed of Light

\(c = 2.997 924 58 E+08 \frac{m}{s}\)

Nuclide	Half-life	Photon Energy (MeV)	HVL (mm Lead)	Exposure Rate Constant (R-cm²/mCi-hr)
¹⁹²Ir	73.8 days	0.38 average	2.5	4.69
²²⁶Ra	1,600 years	0.83 average	12.0	8.25
²²²Rn	3.83 days	0.83 average	12.0	10.15
⁶⁰Co	5.26 years	1.17, 1.33	11.0	13.07
¹³⁷Cs	30.0 years	0.662	5.5	3.26
¹⁹⁸Au	2.7 days	0.412	2.5	2.38
¹²⁵I	59.4 days	0.028 average	0.025	1.46
¹⁰³Pd	17.0 days	0.021 average	0.008	1.48