they say acceleration due to gravity varies with distances,but why its value is always the same?

Question

mani_jha · Answer

It does vary as you go up from the surface of the earth or done below it.  But the change is very little. You can almost ignore it for small distances.

anonymous · Answer

acceleration due gravity is not always constant, it is an inverse square law where if you double the radius, i.e. move from 1 radius to 6400 Km about the Earth then acceleration due to gravity is only 9.8 m/s divided by 4.

anonymous · Answer

The value of 9.8 m/s^2 is the value of acceleration due to gravity at sea level.
as you go higher,the value decreases by the relation 1/r^2 (r = distance)
$$F = GMm/r^2$$|dw:1332860306463:dw|