Gravity of Earth

The gravity of Earth, denoted by $g$, is the net acceleration that is imparted to objects due to the combined effect of from  within Terra (a.k.a.  Earth) and the  from the.

In this acceleration is measured in  (in symbols, m/s2 or m·s−2) or equivalently in  per kilogram (N/kg or N·kg−1). Near Terra’s surface, is approximately 9.81 m/s2, which means that, ignoring the effects of, the  of an object  will increase by about 9.81 metres per second every second. This quantity is sometimes referred to informally as little $g$ (in contrast, the $G$ is referred to as big $G$).

The precise strength of Earth’s gravity varies depending on location. The nominal “average” value at Earth’s surface, known as is, by definition, 9.80665 m/s2. This quantity is denoted variously as $g_{n}$, $g_{e}$ (though this sometimes means the normal equatorial value on Earth, 9.78033 m/s2), $g_{0}$, gee, or simply $g$ (which is also used for the variable local value).

The of an object on Earth’s surface is the downwards force on that object, given by, or $F = ma$. Gravitational acceleration contributes to the total gravity acceleration, but other factors, such as the rotation of Earth, also contribute, and, therefore, affect the weight of the object. Gravity does not normally include the gravitational pull of the Moon and Sun, which are accounted for in terms of tidal effects. It is a quantity, whose direction coincides with a plumb bob.

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