From: utzoo!decvax!harpo!eagle!mhtsa!alice!npoiv!hou5f!ariel!vax135!cornell!uw-beave!uw-june!palmer
Newsgroups: net.physics
Title: Re: Hole through the Earth
Article-I.D.: uw-june.368
Posted: Fri Apr  8 16:17:12 1983
Received: Sun Apr 10 01:46:41 1983
References: uw-beave.474


	The gravity in the hole will be directly proportional to the distance
from the center, so the solution to this problem (ignoring air resistance)
will be exactly the same as a mass on a spring (simple harmonic motion,
r = R sin wt)
	Plugging in the numbers for the earth, I get w=1.24E-3 seconds,
or a period of 84 minutes.
	All this assumes that the Earth is uniform (no dense iron core)
Since this is not true, the actual period will be slightly shorter,
since the gravity does not fall off as rapidly.

	To calculate the air pressure, just take the weight of the column
of air above you.  8km of air at standard pressure and gravity exerts
one atmosphere of force.  You can run the equations through Macsyma if
you want, but I doubt that the air pressure in the center of the tunnel
would be much less than 100,000 atmospheres.

		The double major
		David Palmer