2010-12-20, 07:11 AM
2147483647 Wrote:For lack of a better source, this is visual proof that the acceleration due to gravity changes with r:
http://en.wikipedia.org/wiki/Gravity_of_Earth
Also remember that we calculate gravity from the center of the earth to us, so the radius at the surface is actually about 6440 km, while at a reasonable distance away, say in orbit around the earth, is about 6760 km.


![[Image: erdgvarp.png]](http://img221.imageshack.us/img221/1056/erdgvarp.png)