Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Sunday Morning Puzzle.



At 22:38 10/5/01 -0700, Bernard wrote:
Last week brian w. suggested that a disk of the same mass and radius as
a sphere would have a greater attractive force at the center of its face
(toward the sphere on the pendulum). Rather than stick my neck out, I
pose the Sat. morn. question. (Since most of you won't read this 'till
then.)

What are the respective g fields at the surface of a sphere of radius R
and the center of a face of a disk also radius R and length 4/3 R.
(These better have the same volume, or I'm dead!)

Express in terms of rho (volume density), R, and G

bc



P.s. If you don't want to do the triple integration for the cylinder,
the formula is in the solutions book for the latest ed. of Marian.


I'm not the kind of spoil-sport that wants to squash peoples' natural pleasure
at doing triple integrations over the volumes, but if you'd rather
find results on sight there is the attractive concept sometimes derogated
on the list, called 'center of gravity'. Add to this the idea of inverse r
squared forces versus inverse r forces, and you have a pretty contrast.
(These had better be relevant, or I'm dead too??)
:-)


brian whatcott <inet@intellisys.net> Altus OK
Eureka!