Re: A big whack that made the moon may have also created continents that move

"R Kym Horsell"  wrote in message 
news:[email protected]...

In alt.astronomy Jim Wilkins <[email protected]> wrote:
> ...
> A college physics problem had us integrating the net force of gravity with
> depth, to determine the return time of a weight dropped into a vacuum well
> through Earth (of uniform density). An unexpected result of the calculus 
> was
> that gravitational attraction is zero anywhere within a hollow shell 
> (Dyson
> sphere), only the ball below you attracts.
...

Gauses Theorem (1777-1855).  Applies to spherically symmetric masses.
May not apply to holes rilled through the earth. :)
----------------------

Would the gravity leak out the hole?

The problem set taught us how to devise formulas that describe changing 
conditions, that we could then integrate to determine the value at some 
limit. We weren't expected to accurately model the Earth.