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Re: The Olympics



Well if nothing else do it the easy way. Put one hand over your head, the other at your side and now rotate them in a circle repeatedly on the side (same direction, just like swimming). The rest of your body will rotate in the other direction until your feet have switched places with your head. Then stop rotating your arms. The angular momentum of the arms and the rest of the body balance. You will have to rotate your arms many times to get it to work. Now rotation about the head/foot axis can be achieved by putting one arm over your head with the elbow bent, and rotating it in a circle over your head. Now net displacement needs a trick like sucking in air on the left and blowing it out on the right. However in a space suit net displacement would be impossible without something to throw.

Of course a cat rotates much more quickly by twisting the upper and lower body and tail independently with the legs used to increase or decrease the moment of inertia of each half. And they do it within a couple seconds. Doing this experiment with a young cat onto a soft surface is easy and safe. Cats safely jump from on top of refrigerators to the ground.

John M. Clement
St. Pius X HS



It seems to ME that a stranded, motionless astronaut should be able
to do an 'about-face' maneuver in empty space, ending up motionless,
but facing 180 degrees from the original direction. (without
violating any basic principles!)

If you mean rotating the entire body by 180 degrees (or any amount) it
seems to ME that this is the rotational equivalent to displacing your
body by some amount in empty space. Just as an astronaut can propel one
part of his/her body forward while propeling the rest backward, so s/he
can twist the head around and have the rest rotate oppositely. I don't
see how to generate a net displacement or rotation.

\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\

Doug Craigen
http://www.dctech.com/physics/about_dc.html