14 June 2006

The International Gravity Formula will tell you the acceleration of gravity for your latitude.

This is necessary because the Earth rotates and its rotation creates both a centripetal acceleration (which tends to lift you off the surface a bit) and an oblateness to the planet (which means that the poles are closer to the center of the Earth than the Equator is).

Included on the page is an Excel spreadsheet which will do the math for you. It is conveniently set for the latitude of Philadelphia. (Convenient for me, that is.)