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# Gravitational constant

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The **gravitational constant**, called [math]G[/math] in physics equations, is an empirical physical constant. It is used to show the force between two objects caused by gravity. The gravitational constant appears in Isaac Newton's universal law of gravitation.

[math]G[/math] is about 6.67430×10^{−11} N⋅m^{2}/kg^{2},^{[1]} and is denoted by letter [math]G[/math].

It usually appears in Sir Isaac Newton's law of universal gravitation, and in Albert Einstein's general theory of relativity. It is also known as the **universal gravitational constant**, **Newton's constant**, and colloquially as **Big G**.^{[2]} It should not be confused with "small g" (*g*), which is the local gravitational field of the Earth (equivalent to the free-fall acceleration).^{[3]}

## References

- ↑ "2018 CODATA Value: Newtonian constant of gravitation".
*The NIST Reference on Constants, Units, and Uncertainty*. NIST. 20 May 2019. http://physics.nist.gov/cgi-bin/cuu/Value?bg. Retrieved 2019-05-20. - ↑ Gundlach, Jens H.; Merkowitz, Stephen M. (2002-12-23). "University of Washington Big G Measurement".
*Astrophysics Science Division*. Goddard Space Flight Center. http://asd.gsfc.nasa.gov/Stephen.Merkowitz/G/Big_G.html. "Since Cavendish first measured Newton's Gravitational constant 200 years ago, "Big G" remains one of the most elusive constants in physics." - ↑ Halliday, David; Walker, Jearl; Resnick, Robert (2007).
*WIE ASE Fundamentals of Physics Extended, Eighth Edition, Asian Student Edition*. p. 336. .