1. The problem statement, all variables and given/known data Hiya, I was looking over a General Relativity paper today, and at the end of a question on Geodesic Deviation, was "Give a brief statement of a physical effect or thought-experiment which illustrates how the time sqrt(R/g) characterises the Earth’s gravity." (R is the radius of the earth) 2. Relevant equations t=sqrt(R/g) 3. The attempt at a solution Well, I have been looking through chapters of GR texts on Schwarzchild thought experiments, Bondi thought experiments etc., and can't find anything related to this quantity. Obviously any expression containing g characterises earth's gravity, but I simply don't know what physical effect or thought-experiment the question could be referring to. If anyone could help it would be very much appreciated. Thanks a lot.