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The gravity g′ at depth d is given by g′ = g(1 − d/R) where g is acceleration due to gravity on the surface of the Earth, d is depth and R is the radius of the Earth. If the density decreased linearly with increasing radius from a density ρ 0 at the center to ρ 1 at the surface, then ρ ( r ) = ρ 0 − ( ρ 0 − ρ 1 ) r / R , and the ...
[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]
Gravity is usually measured in units of acceleration.In the SI system of units, the standard unit of acceleration is metres per second squared (m/s 2).Other units include the cgs gal (sometimes known as a galileo, in either case with symbol Gal), which equals 1 centimetre per second squared, and the g (g n), equal to 9.80665 m/s 2.
The result reported by Charles Hutton (1778) suggested a density of 4.5 g/cm 3 (4 + 1 / 2 times the density of water), about 20% below the modern value. [16] This immediately led to estimates on the densities and masses of the Sun, Moon and planets, sent by Hutton to Jérôme Lalande for inclusion in his planetary tables.
For several objects in the Solar System, the value of μ is known to greater accuracy than either G or M. The SI unit of the standard gravitational parameter is m 3 ⋅s −2. However, the unit km 3 ⋅s −2 is frequently used in the scientific literature and in spacecraft navigation.
in which g (φ) is the gravity as a function of the geographic latitude φ of the position whose gravity is to be determined, denotes the gravity at the equator (as determined by measurement), and the coefficients A and B are parameters that must be selected to produce a good global fit to true gravity. [5] Using the values of the GRS80 ...
For example, at a radius of 6600 km (about 200 km above Earth's surface) J 3 /(J 2 r) is about 0.002; i.e., the correction to the "J 2 force" from the "J 3 term" is in the order of 2 permille. The negative value of J 3 implies that for a point mass in Earth's equatorial plane the gravitational force is tilted slightly towards the south due to ...
A common misconception occurs between centre of mass and centre of gravity.They are defined in similar ways but are not exactly the same quantity. Centre of mass is the mathematical description of placing all the mass in the region considered to one position, centre of gravity is a real physical quantity, the point of a body where the gravitational force acts.