SherbyNet - /page/wikibook/entry.mu

Micron Document

<!DOCTYPE html>

<title>Standard gravity</title>

</head>

Standard gravity

</h1>

</header>

The standard acceleration of gravity or standard acceleration of free fall, often called simply standard gravity and denoted by ɡ0 or ɡn, is the nominal <a href="Gravitational_acceleration" title="Gravitational acceleration">gravitational acceleration</a> of an object in a <a href="Vacuum" title="Vacuum">vacuum</a> near the surface of the <a href="Earth" title="Earth">Earth</a>. It is a constant <a href="ISO/IEC_80000" title="ISO/IEC 80000">defined by standard</a> as 9.80665 m/s2 (about 32.17405 ft/s2). This value was established by the third <a href="General_Conference_on_Weights_and_Measures" title="General Conference on Weights and Measures">General Conference on Weights and Measures</a> (1901, CR 70) and used to define the standard <a href="Weight" title="Weight">weight</a> of an object as the product of its mass and this nominal <a href="Acceleration" title="Acceleration">acceleration</a>.<a href="#cite_note-1">[1]</a><a href="#cite_note-2">[2]</a> The acceleration of a body near the surface of the Earth is due to the combined effects of <a href="Gravity" title="Gravity">gravity</a> and <a href="Centrifugal_force" title="Centrifugal force">centrifugal acceleration</a> 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 <a href="Geographical_pole" title="Geographical pole">poles</a> than at the <a href="Equator" title="Equator">Equator</a>.<a href="#cite_note-Boynton-3">[3]</a><a href="#cite_note-4">[4]</a>

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 <a href="Earth's_gravity" class="mw-redirect" title="Earth's gravity">Earth's gravity</a>). The symbol ɡ should not be confused with G, the <a href="Gravitational_constant" title="Gravitational constant">gravitational constant</a>, or g, the symbol for <a href="Gram" title="Gram">gram</a>. The ɡ is also used as a unit for any form of acceleration, with the value defined as above.<style data-mw-deduplicate="TemplateStyles:r1236090951">

/* start https://en.wikipedia.org/ */

.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="G-force" title="G-force">g-force</a></div>

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 <a href="Latitude#Common_"latitude"" title="Latitude">geodetic latitude</a> of 45°. Although the actual acceleration of free fall on Earth varies according to location, the above standard figure is always used for <a href="Metrological" class="mw-redirect" title="Metrological">metrological</a> purposes. In particular, since it is the ratio of the <a href="Kilogram-force" title="Kilogram-force">kilogram-force</a> and the <a href="Kilogram" title="Kilogram">kilogram</a>, its numeric value when expressed in <a href="Coherence_(units_of_measurement)" title="Coherence (units of measurement)">coherent</a> SI units is the ratio of the kilogram-force and the <a href="Newton_(unit)" title="Newton (unit)">newton</a>, two <a href="Force#Units" title="Force">units of force</a>.

<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>

Already in the early days of its existence, the <a href="International_Committee_for_Weights_and_Measures" class="mw-redirect" title="International Committee for Weights and Measures">International Committee for Weights and Measures</a> (CIPM) proceeded to define a standard <a href="Thermometer" title="Thermometer">thermometric</a> scale, using the <a href="Boiling_point" title="Boiling point">boiling point</a> of water. Since the boiling point varies with the <a href="Atmospheric_pressure" title="Atmospheric pressure">atmospheric pressure</a>, the CIPM needed to define a standard atmospheric pressure. The definition they chose was based on the weight of a column of <a href="Mercury_(element)" title="Mercury (element)">mercury</a> 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:

/* start https://en.wikipedia.org/ */

.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}

/* end https://en.wikipedia.org/ */

</style><blockquote class="templatequote">The value of this standard acceleration due to gravity is equal to the acceleration due to gravity at the International Bureau (alongside the <a href="Pavillon_de_Breteuil" title="Pavillon de Breteuil">Pavillon de Breteuil</a>) divided by 1.0003322, the theoretical coefficient required to convert to a latitude of 45° at sea level.<a href="#cite_note-5">[5]</a></blockquote>

All that was needed to obtain a numerical value for standard gravity was now to measure the gravitational strength at the <a href="International_Bureau_of_Weights_and_Measures" title="International Bureau of Weights and Measures">International Bureau</a>. 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.<a href="#cite_note-6">[6]</a>

This result formed the basis for determining the value still used today for standard gravity. The third <a href="General_Conference_on_Weights_and_Measures" title="General Conference on Weights and Measures">General Conference on Weights and Measures</a>, held in 1901, adopted a resolution declaring as follows:

<blockquote class="templatequote">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.<a href="#cite_note-7">[7]</a></blockquote>

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 <a href="Cgs" class="mw-redirect" title="Cgs">cgs</a> system then en vogue – by 1.0003322 while not taking more digits than are warranted considering the uncertainty in the result.

<div class="mw-heading mw-heading2"><h2 id="Conversions">Conversions</h2></div>

<caption>Conversions between common units of acceleration

</caption>

<th scope="col">Base value

</th>

<th scope="col">(<a href="Gal_(unit)" title="Gal (unit)">Gal</a>, or cm/s2)

</th>

<th scope="col">(<a href="Foot_per_second_squared" title="Foot per second squared">ft/s2</a>)

</th>

<th scope="col">(<a href="Metre_per_second_squared" title="Metre per second squared">m/s2</a>)

</th>

<th scope="col">(, g0)

</th></tr>

<tr>

<td>1 Gal, or cm/s2

</td>

<td>1

</td>

<td>0.0328084

</td>

<td>0.01

</td>

<td>1.01972×10−3

</td></tr>

<tr>

<td>1 ft/s2

</td>

<td>30.4800

</td>

<td>1

</td>

<td>0.304800

</td>

<td>0.0310810

</td></tr>

<tr>

<td>1 m/s2

</td>

<td>100

</td>

<td>3.28084

</td>

<td>1

</td>

<td>0.101972

</td></tr>

<tr>

<td>1 g0

</td>

<td>980.665

</td>

<td>32.1740

</td>

<td>9.80665

</td>

<td>1

</td></tr></tbody></table>

<ul><li><a href="Gravity_of_Earth" title="Gravity of Earth">Gravity of Earth</a></li>

<li><a href="Gravity_map" title="Gravity map">Gravity map</a></li>

<li><a href="Seconds_pendulum" title="Seconds pendulum">Seconds pendulum</a></li>

<li><a href="Theoretical_gravity" title="Theoretical gravity">Theoretical gravity</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}

/* end https://en.wikipedia.org/ */

</style><div class="reflist">

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite id="CITEREFTaylorThompson2008" class="citation report cs1">Taylor, Barry N.; Thompson, Ambler, eds. (March 2008). <a rel="nofollow" class="external text" href="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication330e2008.pdf">The international system of units (SI)</a> (PDF) (Report). <a href="National_Institute_of_Standards_and_Technology" title="National Institute of Standards and Technology">National Institute of Standards and Technology</a>. p. 52. NIST special publication 330, 2008 edition.</cite>

</li>

<li id="cite_note-2"><a href="#cite_ref-2">^</a> <cite class="citation book cs1"><a rel="nofollow" class="external text" href="http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf#page=51">The International System of Units (SI)</a> (PDF) (8th ed.). <a href="International_Bureau_of_Weights_and_Measures" title="International Bureau of Weights and Measures">International Bureau of Weights and Measures</a>. 2006. pp. 142–143. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>92-822-2213-6</bdi>.</cite>

</li>

<li id="cite_note-Boynton-3"><a href="#cite_ref-Boynton_3-0">^</a> <cite id="CITEREFBoynton2001" class="citation conference cs1">Boynton, Richard (2001). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20070227132140/http://www.space-electronics.com/Literature/Precise_Measurement_of_Mass.PDF">"Precise Measurement of Mass"</a> (PDF). Sawe Paper No. 3147. Arlington, Texas: S.A.W.E., Inc. Archived from <a rel="nofollow" class="external text" href="http://www.space-electronics.com/Literature/Precise_Measurement_of_Mass.PDF">the original</a> (PDF) on 2007-02-27. Retrieved 2007-01-21.</cite>

</li>

<li id="cite_note-4"><a href="#cite_ref-4">^</a> <a rel="nofollow" class="external text" href="http://curious.astro.cornell.edu/question.php?number=310">"Curious About Astronomy?"</a>, Cornell University, retrieved June 2007

</li>

<li id="cite_note-5"><a href="#cite_ref-5">^</a> <cite id="CITEREFTerry_Quinn2011" class="citation book cs1">Terry Quinn (2011). From Artefacts to Atoms: The BIPM and the Search for Ultimate Measurement Standards. <a href="Oxford_University_Press" title="Oxford University Press">Oxford University Press</a>. p. 127. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-19-530786-3</bdi>.</cite>

</li>

<li id="cite_note-6"><a href="#cite_ref-6">^</a> <cite id="CITEREFM._Amalvict2010" class="citation conference cs1">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. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-3-642-10634-7</bdi>.</cite>

</li>

<li id="cite_note-7"><a href="#cite_ref-7">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.bipm.org/en/committees/cg/cgpm/3-1901/resolution-2">"Resolution of the 3rd CGPM (1901)"</a>. <a href="BIPM" class="mw-redirect" title="BIPM">BIPM</a>. Retrieved July 19, 2015.</cite>

</li>

</ol></div></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-06-30" href="https://en.wikipedia.org/wiki/?title=Standard_gravity&oldid=1298062037">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

</div>

</div></div>

</div>

</main>

</div>

</body></html>