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Re: value of g in black holes



Vic Decarlo wrote:

I'm teaching a course on black holes this semester using
the new excellent new intro text by Taylor and Wheeler
("Exploring Black Holes"). One of the exercises involves
calculating the local acceleration of gravity for someone
standing on a shell of reduced circumference R surrounding
a nonspinning, spherical black hole of mass M. The answer
turns out to be

g = (M/R^2) / sqrt(1 - 2M/R)

Well, as I said my formula was probably wrong :-)
Now educate me: can you give me a simple derivation of the sqrt
factor in the above expression?
--
Carl E. Mungan, Asst. Prof. of Physics 410-293-6680 (O) -3729 (F)
U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mungan@usna.edu http://physics.usna.edu/physics/faculty/mungan/