[TLE2]

Found this on Yahoo Answers:

Altitude
Acceleration due to gravity decreases as the inverse of the square of the distance from the center of mass of the body imparting the gravitational acceleration; g=k/x2
Because the earth is not perfectly spherical, the distance from the center of the earth for any person standing on the surface depends upon the latitude L.
The equatorial radius of the earth is approximately 6,378,140 meters.
The polar radius is approximately 6,356,755 meters.
If we model the earth as an ellipsoid, this means that the radius of the earth at latitude L is given by R= 6,356,755* sqrt( 1 + .0067396*cos2(L) ).
At the latitude of Terre Haute, this is approximately 6,369,502 meters.
Thus, a person at altitude of H meters above sea level experiences and acceleration due to gravity of
a= g*R2/(R+H)2.
G310 is at approximately 580 feet above sea level. This is roughly 176.8 meters above sea level.
This gives an acceleration due to gravity of approximately 9.8095794 meters per second2.
Moving to the classroom ceiling, this constant becomes 9.8095701 meters per second2.
Moving to the circle in front of Hadley Hall (L-> .689103, H->180m), we get an acceleration due to gravity of approximately 9.80956953 meters per second2.