# Gravity Definitions for Land Surveyors

gravimeter-1 Instrument for measuring variations in the magnitude of the gravitational field of the Earth. 2 In geodesy, a weighing device or instrument of sufficient sensitivity to register variations in the weight of a constant mass when the mass is moved from place to place on the Earth, thereby subjecting it to the influence of gravity at those places.

gravimetric survey—A survey made to determine the force of gravity at various places on the Earth\’s surface.

gravity-1 The gravitational force (as modified by centrifugal force due to rotation) exerted by the Earth on bodies at or near its surface, which results in their having weight. 2 The effect, on any body, of the gravitational attraction by all other bodies and of any centrifugal force which may act upon it. 3 The force exerted, at a point, by the gravitational attraction of all bodies acting at that point and by the revolution of that point about a given axis. 4 A unit of acceleration equal to the acceleration resulting from the average force of gravity at the Earth’s surface. By international agreement this unit is equal to 980.665 centimeters per second.

gravity correction-1A quantity added to a theoretical value of the gravity to obtain a better approximation to the measured value. 2 A quantity added to a measured value to obtain a theoretical value of the gravity. The quantities in definitions (1) and (2) are of equal absolute value and opposite signs.

gravity potential-1The potential created, at a point rotating with the Earth, by the combined action of gravitational and centrifugal forces. 2 The gravity potential per unit mass of the body creating the potential. 3 The quantity whose directional derivative is the negative of the acceleration of gravity. 4 The work done in moving a body of unit mass from one point on a rotating, massive body to another point on or rotating with the same body.

Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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