Re: The Olympics

[Doug Craigen <dcc@ESCAPE.CA>]

John Barrer wrote:
> Suppose a diver leaves the platform with NO angular
> momentum. If she then bends at the waist, the Earth
> can then supply the external torque to initiate
> rotation. Now there is plenty of angular momentum

I don't see how the earth can apply a net torque to a body in free
fall.  Can you draw a free body diagram that shows how this would
happen?

> available to be conserved. Of course, if this is true,
> then it would be impossible to start the routine with
> a twist. A "tumble" (or some other rotation caused by
> the diver orienting a portion of her body so that an
> external torque would be supplied by the Earth) would
> have to initiate the dive or any other similar move.
> Is this so?? John Barrere   Apex HS  Apex, NC

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