Selected Physical Constants
- Page ID
- 89965
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| Physical Constant | Value |
|---|---|
| Speed of light in a vacuum | \(\begin{array}{l} c=2.99792458 \times\left\{\begin{array}{l} 10 \text { meters/second } \\ 10^{10} \text { centimeters/second } \end{array}\right \\ \\ c=\left\{\begin{array}{l} 1 \text { meter of distance/meter of light-travel time } \\ 1 \text { centimeter of distance/centimeter of light-travel time } \end{array}\right. \end{array}\) |
| Gravitational constant | \(G=6.673 \times\left\{\begin{array}{l}10)^{-11} \text { meter }^5 /\left(\text { kilogram-second }^{\prime}\right) \\10^{-8} \text { centimeter } /(\text { gram-second }\end{array}\right.\) |
| Planck constant | \(h=6.6261 \times\left\{\begin{array}{ll}10^{-11} & \text { kilogram-meter }{ }^2 / \text { second }^2 \\ 10^{-27} & \text { gram-centimeter } / \text { second }^2\end{array}\right.\) |
| Boltzmann constant | \(k=1.38066 \times\left\{\begin{array}{l}10^{-14} \text { joule/degree Kelvin } \\ 10^{-16} \mathrm{erg} / \text { degree Kelvin }\end{array}\right.\) |
| Elementary charge | \(e=\left\{\begin{array}{l}1.60218 \times 10^{-19} \text { coulombs } \\ 4.80321 \times 10^{-10} \text { esu or }\left(\text { gram centimeter } / \text { second }^2\right)^{1 / 2}\end{array}\right.\) |
| Electron mass | \(m_i=9.1094 \times\left\{\begin{array}{l}10^{-31} \text { kilogram } \\ 10^{-2 \mathrm{H}} \text { gram }\end{array}\right.\) |
| Electron rest energy | \(\begin{aligned} m_c c^2 & =8.1871 \times\left\{\begin{array}{l}10^{-11} \text { joules } \\ 10^{-7} \text { ergs }\end{array}\right. \\ & =0.510999 \mathrm{MeV}\end{aligned}\) |
| Proton mass | \(m_p=1.67262 \times\left\{\begin{array}{l}10^{-27} \text { kilogram } \\ 10^{-21} \text { gram }\end{array}\right.\) |
| Proton rest energy | \(\begin{aligned}m_p c^2 & =1.503279 \times\left\{\begin{array}{l}10^{-10} \text { joules } \\10^{-3} \mathrm{ergs}\end{array}\right. \\& =938.272 \mathrm{MeV}\end{aligned}\) |
| Mass of Earth | \(M_{\oplus}=5.9742 \times\left\{\begin{array}{l}10^{21} \text { kilograms } \\ 10^{27} \text { grams }\end{array}\right.\) |
| Radius of a sphere having the same volume as Earth | \(R_{\oplus}=6.3710 \times\left\{\begin{array}{l}10^6 \text { meters } \\ 10^s \text { centimeters }\end{array}\right.\) |
| Mean distance of Earth from Sun = "astronomical unit" | \(AU=1.495978 \times\left\{\begin{array}{l}10^{11} \text { meters } \\ 10^{13} \text { centimeters }\end{array}\right.\) |
| Mean speed of Earth in its orbit about Sun | \( v=29.78 \text { kilometers/second }\) |
| Mean distance of Moon from Earth | \( 3.844 \times\left\{\begin{array}{l} 10^* \text { meters } \\ 10^{10} \text { centimeters }\end{array} \right.\) |
| Mass of Sun | \(M_{\odot}=1.989 \times\left\{\begin{array}{l}10^{30} \text { kilograms } \\ 10^{53} \text { grams }\end{array}\right.\) |
| Mean radius of Sun | \(R_0=6.9599 \times\left\{\begin{array}{l}10^k \text { meters } \\ 10^{10} \text { centimeters }\end{array}\right.\) |
Conversion Factors
| From | To |
|---|---|
| 1 second | \(=2.99792458 \times\left\{\begin{array}{l}10^8 \text { meters } \\ 10^{10} \text { centimeters }\end{array}\right\}\) of light-travel time |
| 1 meter of light time travel | \(=3.335641 \times 10^{-9}\) second |
| 1 centimeter of light time travel | \(=3.335641 \times 10^{-11}\) second |
| 1 year | \(=3.156 \times 10^7\) seconds \(=9.460 \times\left\{\begin{array}{l}10^{15} \text { meters } \\ 10^{17} \text { centimeters }\end{array}\right\}\) of light-travel time |
| 1 kilometer | \(=0.6214\) mile |
| 1 electron-volt | \(=1.602 \times 10^{-19}\) joule \(=1.602 \times 10^{-12} \mathrm{erg}\) |