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Re: [Phys-l] Centrifugal redux



On 03/20/2009 06:58 AM, chuck britton wrote:

Can't I say - that I am ALWAYS in my OWN ref frame?

You can choose whatever frame you like.

It is not, however, a _free_ choice, since it comes at a cost.

If you choose anything other than a Newtonian frame, Newton's
laws (in their usual form) do not apply. To say the same thing
the other way, if you are willing to deal with non-Newtonian
equations of motion, then using a frame tied to your arbitrarily
accelerated and/or rotating self is a viable choice.

Then the gas pedal DID give motion to the charge.

In a non-Newtonian frame, the equations of electromagnetism pick
up additional frame-dependent terms, so you have additional work
to do. It's doable but messy.

Or must I always keep a cup of coffee in my lap - to let me know when
I have shifted to a new frame.

You can choose any frame you like, so long as your physics machinery
is sophisticated enough to handle it.

This doesn't seem right - since folks are saying that a satellite is
in it's own frame - NOT constantly shifting from one to another.

The satellite is presumably in a freely-falling reference frame.
In such a frame, the physics is as simple as it possibly could be,
even simpler than in the familiar terrestrial "lab frame".

Choosing an ultra-simple reference frame is different from choosing
an ultra-complicated reference frame.

So I DIDn't move to a new frame
My almighty gas pedal was able to push the entire universe backward!!!!

It's your choice ... but you must accept the consequences of
your choice.

And this backward accelerating universe is 'responsible' for the
increased normal force on my back.

General Rel. unites Gravity with E&M.

Not united in the sense of "unified field theory". You can do GR
without EM and vice versa. This stands in dramatic consequence to
Maxwell's electromagnetism, which truly unites E with M. That is,
in a universe consistent with special relativity (or even Galilean
relativity) you can't have E without M or M without E ... which is
what we usually mean by "united".