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: point particles



Isn't it so that (I think it's Chasle's theorem):
The instantaneous general motion of any rigid body can be viewed as the
compounding of
1) a pure translational motion of the body, and
2) a rotation about any freely choosable point fixed in the (extended) body.

It follows that if one rides on a fixed body point and observes the body,
only a pure rotation will be directly observed at any instant.
I think this is quite intuitive.

Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
http://www.velocity.net/~trebor/
trebor@velocity.net
----- Original Message -----
From: "John Mallinckrodt" <ajm@CSUPOMONA.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Thursday, January 22, 2004 3:01 PM
Subject: Re: point particles
. . .

So here's a small "paradox" that may be further enlightening to
resolve: In the accelerating frame, the torque is produced by the
combined action of electric and gravitational forces. But the
electric force acts at one END of the rod while the gravitational
force is distributed and can be considered (as usual) to act at the
CENTER of the rod. This being the case, why does the rod oscillate
about its center?

John Mallinckrodt
Cal Poly Pomona