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Re: operationally inertial frames



At 09:19 AM 10/13/99 -0800, John Mallinckrodt wrote:

I don't think it's nitpicking to point out that, if the shaking of the
earth were at all fast, the structure of the earth would be altered
(shape, Etc., crushed? smashed?) from the application of the forces needed
to do the job. I think that would be pretty noticeable, locally and
globally.

Not true. The forces are applied inertially so there is exactly zero
deformation.

Hmmmm. I wouldn't have said that. That's not the usual definition of
"shaking the earth". Perhaps the physical picture that JM is trying to
communicate corresponds more closely to a rapidly-time-dependent
acceleration (i.e. shaking) _of the reference frame_. That would make the
equations of motion very messy but would obviously have no effect on the
physics of the physical objects under study.

It is important to realize that it is not necessary, wise, or customary to
insist that the reference frame be attached to the object(s) under study.


______________________________________________________________
copyright (C) 1999 John S. Denker jsd@monmouth.com