What Is Standard Gravity?

Valerie Clark

By definition, standard gravity is the acceleration of a body if it were in a vacuum at or near the surface of the Earth, and it is defined numerically as 9.80665 meters per second squared (m/s2), which is 32.174 feet per second squared, and represented as g0 or gn. Standard gravity is the result of centrifugal acceleration and gravity. It is also known as standard acceleration caused by free fall, standard acceleration of gravity and standard Earth gravity.

Standard gravity is also known as standard acceleration caused by free fall.
Standard gravity is also known as standard acceleration caused by free fall.

The standard gravity (g0) value, rounded to 9.807 m/s2, represents a mid-range value based on an object in free fall at sea level at 45 degrees latitude. The standard gravity constant is widely used for meteorological purposes, but the actual value varies based on the specific location of an object. The average sea-level acceleration on Earth is actually slightly smaller than 9.807 m/s2.

The international unit for standard gravity is meters per square second, the same as that used for acceleration and specific force. Specific force is expressed as Newtons per kilogram (N/kg). Therefore, it becomes clear that the standard gravity is a function of force, expressed in Newtons, and mass, expressed in kilograms. Thus, standard gravity also can be written as 9.807 N/kg. This representation shows that each kilogram of mass is associated with a standard gravitation field equivalent to 9.806 Newtons, which translates to what we define as weight on Earth.

The actual determination of weight might be better calculated with special consideration for the local acceleration of gravity based on altitude or latitude. Adjustments for altitude, latitude and the Earth’s radius can be factored in to show how an object will weigh more at higher latitudes than it would closer to the equator. This fact is largely because of the oblong shape of the Earth, which creates a gravitational pull that is weakest at the equator and strongest at the poles.

The standard gravity measurement was established in 1901 at the third Conférence Génèrale des Poids et Mesures (CGPM). The CGPM world conference met in 1901 to clarify the definitions of mass versus weight. The first conference commenced in 1889 in Paris and reconvenes every four years to authorize metric measurements for the international system for units and measurements.

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