Acceleration due to gravity: Difference between revisions
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In the [[science]]s the term '''acceleration due to gravity''' commonly refers to the value | In the [[science]]s, the term '''acceleration due to gravity''' commonly refers to the value of 9.80656 m/s<sup>2</sup> and is denoted as ''g<sub>n</sub>''. That value was agreed upon by the 3rd General Conference on Weights and Measures (Conférence Générale des Poids et Mesures, CGPM) in 1901.<ref>[http://physics.nist.gov/Document/sp330.pdf The International System of Units (SI), NIST Special Publication 330, 2001 Edition] (pdf page 29 of 77 pdf pages) </ref><ref>[http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf#page=51 Bureau International des Poids et Mesures] (pdf page 51 of 88 pdf pages)</ref> It is also often referred to as the ''local gravitational acceleration'' or the ''standard gravity''. | ||
Any object near the [[earth]] is subject to a [[force]] in the downward direction that causes an [[acceleration]] of magnitude ''g'' toward the surface of the earth. This value serves as an excellent approximation for the local acceleration due to gravity at the surface of the earth, although it is not exact and the actual acceleration varies slightly between different locations around the world. | Any object near the [[earth]] is subject to a [[force]] in the downward direction that causes an [[acceleration]] of magnitude ''g<sub>n</sub>'' toward the surface of the earth. This value serves as an excellent approximation for the local acceleration due to gravity at the surface of the earth, although it is not exact and the actual acceleration varies slightly between different locations around the world. | ||
More generally the acceleration due to gravity refers to the magnitude and direction of the acceleration of some test object due to the [[mass]] of another object. | More generally the acceleration due to gravity refers to the magnitude and direction of the acceleration of some test object due to the [[mass]] of another object. | ||
Under [[Newtonian gravity]] the gravitational field strength, or gravitational acceleration, due to a [[spherical symmetry|spherically symmetric]] object of mass ''M'' is given by | Under [[Newtonian gravity]] the gravitational field strength, or gravitational acceleration, due to a [[spherical symmetry|spherically symmetric]] object of mass ''M'' is given by: | ||
:<math>\vec g = -G \frac{M}{r^2} \frac{\vec{r}}{r} | :<math>\vec g = -G \frac{M}{r^2} \frac{\vec{r}}{r}</math> | ||
The magnitude of the acceleration is <math>g = GM/r^2</math>, with [[SI]] units of [[meter]]s per [[second]] squared. | The magnitude of the acceleration is <math>g = GM/r^2</math>, with [[SI]] units of [[meter]]s per [[second]] squared | ||
Here ''G'' is the [[universal gravitational constant]], ''G'' = 6.67428×10<sup>−11</sup> Nm<sup>2</sup>/kg<sup>2</sup>,<ref> Source: [http://physics.nist.gov/cgi-bin/cuu/Value?bg|search_for=Gravitational CODATA 2006, retrieved 2/24/08 from NIST website]</ref> <math>\vec r</math> is the position of the test object in the field relative to the centre of mass ''M'', and ''r'' is the magnitude (length) of <math>\vec{r}</math>. | |||
==Reference== | ==Reference== | ||
<references /> | <references /> | ||
Revision as of 02:35, 26 February 2008
In the sciences, the term acceleration due to gravity commonly refers to the value of 9.80656 m/s2 and is denoted as gn. That value was agreed upon by the 3rd General Conference on Weights and Measures (Conférence Générale des Poids et Mesures, CGPM) in 1901.[1][2] It is also often referred to as the local gravitational acceleration or the standard gravity.
Any object near the earth is subject to a force in the downward direction that causes an acceleration of magnitude gn toward the surface of the earth. This value serves as an excellent approximation for the local acceleration due to gravity at the surface of the earth, although it is not exact and the actual acceleration varies slightly between different locations around the world.
More generally the acceleration due to gravity refers to the magnitude and direction of the acceleration of some test object due to the mass of another object. Under Newtonian gravity the gravitational field strength, or gravitational acceleration, due to a spherically symmetric object of mass M is given by:
The magnitude of the acceleration is , with SI units of meters per second squared
Here G is the universal gravitational constant, G = 6.67428×10−11 Nm2/kg2,[3] is the position of the test object in the field relative to the centre of mass M, and r is the magnitude (length) of .
Reference
- ↑ The International System of Units (SI), NIST Special Publication 330, 2001 Edition (pdf page 29 of 77 pdf pages)
- ↑ Bureau International des Poids et Mesures (pdf page 51 of 88 pdf pages)
- ↑ Source: CODATA 2006, retrieved 2/24/08 from NIST website