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Physics LibreTexts

Selected Physical Constants

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Physical Constant Value
Speed of light in a vacuum c=2.99792458×{10 meters/second 1010 centimeters/second \c={1 meter of distance/meter of light-travel time 1 centimeter of distance/centimeter of light-travel time 
Gravitational constant G=6.673×{10)11 meter 5/( kilogram-second )108 centimeter /( gram-second 
Planck constant h=6.6261×{1011 kilogram-meter 2/ second 21027 gram-centimeter / second 2
Boltzmann constant k=1.38066×{1014 joule/degree Kelvin 1016erg/ degree Kelvin 
Elementary charge e={1.60218×1019 coulombs 4.80321×1010 esu or ( gram centimeter / second 2)1/2
Electron mass mi=9.1094×{1031 kilogram 102H gram 
Electron rest energy mcc2=8.1871×{1011 joules 107 ergs =0.510999MeV
Proton mass mp=1.67262×{1027 kilogram 1021 gram 
Proton rest energy mpc2=1.503279×{1010 joules 103ergs=938.272MeV
Mass of Earth M=5.9742×{1021 kilograms 1027 grams 
Radius of a sphere having the same volume as Earth R=6.3710×{106 meters 10s centimeters 
Mean distance of Earth from Sun = "astronomical unit" AU=1.495978×{1011 meters 1013 centimeters 
Mean speed of Earth in its orbit about Sun v=29.78 kilometers/second 
Mean distance of Moon from Earth 3.844×{10 meters 1010 centimeters 
Mass of Sun M=1.989×{1030 kilograms 1053 grams 
Mean radius of Sun R0=6.9599×{10k meters 1010 centimeters 

Conversion Factors

From To
1 second =2.99792458×{108 meters 1010 centimeters } of light-travel time
1 meter of light time travel =3.335641×109 second
1 centimeter of light time travel =3.335641×1011 second
1 year =3.156×107 seconds =9.460×{1015 meters 1017 centimeters } of light-travel time
1 kilometer =0.6214 mile
1 electron-volt =1.602×1019 joule =1.602×1012erg
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