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Re: MOMENT OF INERTIA




Nor can you begin to spin; nor can you fall forward, which in one sense is
the same thing as spinning.

Mervin Koehlinger
Physics Instructor
Concordia Lutheran High School
Fort Wayne, Indiana

Howdy,

It is possible to rotate your body to face a different direction without
violating angular momentum conservation. The trick is to realize that
angular momentum is a vector law and that you can divide your body into two
sub-bodies that can rotate "against" each other. By changing the moment of
inertia of the upper and lower parts of the body appropriately you can have
DIFFERENT and opposite angular velocities so the different parts of the
body will rotate through different angles in the same amount of time.
Change the relative I's and go the other way and the body is now facing a
different direction.

That's how we aim camera's at different points in space without using fuel
"jets"! Spin an internal body one way and the rest of the satellite
rotates the other way.

Good Luck,

Herb Schulz
(herbs@interaccess.com)