# What is difference between Acceleration due to gravity and Gravitational field intensity near the Earth Surface?

I have read in so many standard books that Gravitational field intensity near the earth surface and acceleration due to gravity near the earth surface are Two Different physical quantities with same Direction, Magnitude and Units. So if All the units magnitudes and directions are same and also both mean the acceleration produced in a point mass near the earth surface What is difference between them?

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Could you mention/quote which book says that? –  jinawee Jan 30 at 22:35

Gravitational Intensity and Gravitation acceleration , even though have same dimensions are different physical quantities.

Gravitational Intensity of a mass body A at a given point is defined as the force on a unit mass body. It is just a physical quantity that is defined to help us find out the force exerted by the mass body A on any given mass in its field. So, if at any particular instant the gravitational intensity at a given is E , it does not imply that the gravitational acceleration of any mass at that point is equal to E, it's gravitational acceleration corresponds to the resultant force on it due to other bodies . For eg. Consider Moon, to find out the force exerted by the sun on it, we find out the gravitational intensity of the Sun at that point , but that does not mean that it is the gravitational acceleration.

Even for an isolated system of two bodies, gravitational intensity at a point is the property of the gravitational field associated with the mass A in consideration above, while the gravitational acceleration is the property of the other mass which is present in mass A 's gravitational field, that is even if the other body isn't present, gravitational intensity will be defined whereas gravitational acceleration will not be.

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And what does the electric field have to do with gravity? –  Brandon Enright Feb 3 at 4:21
-1. Please clarify your definitions of "gravitational intensity" and "gravitational acceleration". With the definitions I'd go with (g-field as the sum of all fields produced by all point masses) the statement "it does not imply that the gravitational acceleration of any [point] mass at that point is equal to E" is false. (the field produced by the point mass itself is ignored) –  NeuroFuzzy Feb 3 at 6:23

Dimension of Acceleration due to Gravity: $LT^{−2}$

Dimension of Gravitational Field Intensity: $MLT^{-2}M^{-1} = LT^{-2}$

As dimensions of both are same, both are same physical quantities. All those physics books saying them different are wrong.

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Are you sure? It is also written in HC Verma. –  Dvij Jan 31 at 3:13
Despite its popularity in India, HC Verma is one of worst books on the Earth just to confuse your concepts. Avoid it at any cost. –  Sachin Shekhar Jan 31 at 8:23

1) Gravitation, due to mass alone, is acceleration, m/sec^2.

2) Gravity includes Earth's spin and explains how plumb lines are still normal to the (smooth) surface. Spin also enters gravitomagnetic effects like frame dragging.

3) Gravitational potential explains tides and changes the observed rate of clocks versus their altitude, J/kg. The gravitational field, acceleration of a test mass near a massive object, is the negative gradient of the gravitational potential. In GR, it is replaced by the metric tensor.

4) Gravitational field is phenomenological, N/kg.

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