The standard acceleration due to gravity (or standard acceleration of free fall), sometimes abbreviated as standard gravity, usually denoted by ɡ0 or ɡn, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is defined by standard as 9.80665 m/s2 (about 32.17405 ft/s2). This value was established by the 3rd CGPM (1901, CR 70) and used to define the standard weight of an object as the product of its mass and this nominal acceleration.[1][2] The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from the rotation of the Earth (but the latter is small enough to be negligible for most purposes); the total (the apparent gravity) is about 0.5% greater at the poles than at the Equator.[3][4]
Although the symbol ɡ is sometimes used for standard gravity, ɡ (without a suffix) can also mean the local acceleration due to local gravity and centrifugal acceleration, which varies depending on one's position on Earth (see Earth's gravity). The symbol ɡ should not be confused with G, the gravitational constant, or g, the symbol for gram. The ɡ is also used as a unit for any form of acceleration, with the value defined as above; see g-force.
The value of ɡ0 defined above is a nominal midrange value on Earth, originally based on the acceleration of a body in free fall at sea level at a geodetic latitude of 45°. Although the actual acceleration of free fall on Earth varies according to location, the above standard figure is always used for metrological purposes. In particular, since it is the ratio of the kilogram-force and the kilogram, its numeric value when expressed in coherent SI units is the ratio of the kilogram-force and the newton, two units of force.
Already in the early days of its existence, the International Committee for Weights and Measures (CIPM) proceeded to define a standard thermometric scale, using the boiling point of water. Since the boiling point varies with the atmospheric pressure, the CIPM needed to define a standard atmospheric pressure. The definition they chose was based on the weight of a column of mercury of 760 mm. But since that weight depends on the local gravity, they now also needed a standard gravity. The 1887 CIPM meeting decided as follows:
The value of this standard acceleration due to gravity is equal to the acceleration due to gravity at the International Bureau (alongside the Pavillon de Breteuil) divided by 1.0003322, the theoretical coefficient required to convert to a latitude of 45° at sea level.[5]
All that was needed to obtain a numerical value for standard gravity was now to measure the gravitational strength at the International Bureau. This task was given to Gilbert Étienne Defforges of the Geographic Service of the French Army. The value he found, based on measurements taken in March and April 1888, was 9.80991(5) m⋅s−2.[6]
This result formed the basis for determining the value still used today for standard gravity. The third General Conference on Weights and Measures, held in 1901, adopted a resolution declaring as follows:
The value adopted in the International Service of Weights and Measures for the standard acceleration due to Earth's gravity is 980.665 cm/s2, value already stated in the laws of some countries.[7]
The numeric value adopted for ɡ0 was, in accordance with the 1887 CIPM declaration, obtained by dividing Defforges's result – 980.991 cm⋅s−2 in the cgs system then en vogue – by 1.0003322 while not taking more digits than warranted considering the uncertainty in the result.
^Taylor, Barry N.; Thompson, Ambler, eds. (March 2008). The international system of units (SI) (PDF) (Report). National Institute of Standards and Technology. p. 52. NIST special publication 330, 2008 edition.
^M. Amalvict (2010). "Chapter 12. Absolute gravimetry at BIPM, Sèvres (France), at the time of Dr. Akihiko Sakuma". In Stelios P. Mertikas (ed.). Gravity, Geoid and Earth Observation: IAG Commission 2: Gravity Field. Springer. pp. 84–85. ISBN978-3-642-10634-7.
^"Resolution of the 3rd CGPM (1901)". BIPM. Retrieved July 19, 2015.
March 18, 2023
standard, gravity, standard, acceleration, gravity, standard, acceleration, free, fall, sometimes, abbreviated, standard, gravity, usually, denoted, nominal, gravitational, acceleration, object, vacuum, near, surface, earth, defined, standard, 80665, about, 17. The standard acceleration due to gravity or standard acceleration of free fall sometimes abbreviated as standard gravity usually denoted by ɡ0 or ɡn is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth It is defined by standard as 9 80665 m s2 about 32 17405 ft s2 This value was established by the 3rd CGPM 1901 CR 70 and used to define the standard weight of an object as the product of its mass and this nominal acceleration 1 2 The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from the rotation of the Earth but the latter is small enough to be negligible for most purposes the total the apparent gravity is about 0 5 greater at the poles than at the Equator 3 4 Although the symbol ɡ is sometimes used for standard gravity ɡ without a suffix can also mean the local acceleration due to local gravity and centrifugal acceleration which varies depending on one s position on Earth see Earth s gravity The symbol ɡ should not be confused with G the gravitational constant or g the symbol for gram The ɡ is also used as a unit for any form of acceleration with the value defined as above see g force The value of ɡ0 defined above is a nominal midrange value on Earth originally based on the acceleration of a body in free fall at sea level at a geodetic latitude of 45 Although the actual acceleration of free fall on Earth varies according to location the above standard figure is always used for metrological purposes In particular since it is the ratio of the kilogram force and the kilogram its numeric value when expressed in coherent SI units is the ratio of the kilogram force and the newton two units of force Contents 1 History 2 Conversions 3 See also 4 ReferencesHistory EditAlready in the early days of its existence the International Committee for Weights and Measures CIPM proceeded to define a standard thermometric scale using the boiling point of water Since the boiling point varies with the atmospheric pressure the CIPM needed to define a standard atmospheric pressure The definition they chose was based on the weight of a column of mercury of 760 mm But since that weight depends on the local gravity they now also needed a standard gravity The 1887 CIPM meeting decided as follows The value of this standard acceleration due to gravity is equal to the acceleration due to gravity at the International Bureau alongside the Pavillon de Breteuil divided by 1 0003322 the theoretical coefficient required to convert to a latitude of 45 at sea level 5 All that was needed to obtain a numerical value for standard gravity was now to measure the gravitational strength at the International Bureau This task was given to Gilbert Etienne Defforges of the Geographic Service of the French Army The value he found based on measurements taken in March and April 1888 was 9 80991 5 m s 2 6 This result formed the basis for determining the value still used today for standard gravity The third General Conference on Weights and Measures held in 1901 adopted a resolution declaring as follows The value adopted in the International Service of Weights and Measures for the standard acceleration due to Earth s gravity is 980 665 cm s2 value already stated in the laws of some countries 7 The numeric value adopted for ɡ0 was in accordance with the 1887 CIPM declaration obtained by dividing Defforges s result 980 991 cm s 2 in the cgs system then en vogue by 1 0003322 while not taking more digits than warranted considering the uncertainty in the result Conversions EditConversions between common units of acceleration Base value Gal or cm s2 ft s2 m s2 Standard gravity g0 1 Gal or cm s2 1 0 0328084 0 01 1 01972 10 31 ft s2 30 4800 1 0 304800 0 03108101 m s2 100 3 28084 1 0 1019721 g0 980 665 32 1740 9 80665 1See also EditGravity of Earth Seconds pendulum Theoretical gravityReferences Edit Taylor Barry N Thompson Ambler eds March 2008 The international system of units SI PDF Report National Institute of Standards and Technology p 52 NIST special publication 330 2008 edition The International System of Units SI PDF 8th ed Bureau international des poids et mesures 2006 pp 142 143 ISBN 92 822 2213 6 Boynton Richard 2001 Precise Measurement of Mass PDF Sawe Paper No 3147 Arlington Texas S A W E Inc Retrieved 2007 01 21 Curious About Astronomy Cornell University retrieved June 2007 Terry Quinn 2011 From Artefacts to Atoms The BIPM and the Search for Ultimate Measurement Standards Oxford University Press p 127 ISBN 978 0 19 530786 3 M Amalvict 2010 Chapter 12 Absolute gravimetry at BIPM Sevres France at the time of Dr Akihiko Sakuma In Stelios P Mertikas ed Gravity Geoid and Earth Observation IAG Commission 2 Gravity Field Springer pp 84 85 ISBN 978 3 642 10634 7 Resolution of the 3rd CGPM 1901 BIPM Retrieved July 19 2015 Retrieved from https en wikipedia org w index php title Standard gravity amp oldid 1132514022, wikipedia, wiki, book, books, library,
