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'Standard gravity', usually denoted by ''g''₀ or ''g''_n, is the nominal acceleration due to gravity at the Earth's surface at sea level. By definition it is equal to exactly 9.80665  m·s⁻² (approx. 32.174 ft·s⁻²).^[1] This value was established by the 3rd CGPM (1901, CR 70).
The symbol ''g'' is sometimes also used for standard gravity, but ''g'' strictly means the local acceleration due to gravity, which varies depending on one's position on Earth. The symbol ''g'' should not be confused with ''G'', the gravitational constant, or g, the abbreviation for gram (which is not italicized). The ''g'' (pronounced "gee") is also used as a unit of acceleration, with the value defined as above; see g-force.
The value of ''g''₀ defined above is an arbitrary midrange value on Earth, approximately equal to the acceleration of a body in free fall (in the absence of air resistance) at sea level at a geodetic latitude of about 45.5°. It is larger in magnitude than the average sea level acceleration on Earth, which is about 9.797 645 m·s⁻². Although the actual strength of gravity on Earth varies according to location (see Earth's gravity), for weights and measures and many calculation purposes the standard gravity figure is used.
The SI units of acceleration due to gravity (or, indeed, any acceleration), namely meters per square second, are interchangeable with newtons per kilogram. The numerical value, 9.80665, stays the same. These alternative units may be more intuitive when considering problems involving pressure due to gravity, or weight. For example, under standard gravity a mass of 1 kilogram exerts a weight force of 9.80665 newtons.

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References

1. The notation ''m·s⁻²'' means ''meters per second per second'', and the notation ''ft·s⁻²'' means ''feet per second per second''.

See also

★ Earth's gravity

★ g-force, a measure of apparent acceleration

★ ''G'', the gravitational constant in Newton's law of gravity

External Links

★ http://physics.nist.gov/Document/sp330.pdf (pg.29 in document or pg. 39 of pdf)

★ http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf (pg.143 in document or pg. 51 of pdf)