Re: car acceleration

[John Barrer <forcejb@YAHOO.COM>]

That's EXACTLY the point (or points) I was
unsuccessfully trying to make. John Barrere
--- Rick Tarara <rtarara@SAINTMARYS.EDU> wrote:
> On the other hand, let's go back to the deformation
> idea.  While John D.
> rejects this, it does seem to me that this has been
> used to preserve WE and
> 'real' work.  The 'reasoning' goes like this (I
> believe).  During the push
> there MUST be some deformation of the wall.  That
> deformation may be very
> small, but then the forces are very large.  Energy
> is stored in the deformed
> wall BUT came from the person.  As the wall rebounds
> there is a force
> (perhaps quite large) that acts through a
> displacement (perhaps quite small)
> that will account for the change in KE of the
> person.  In the end analysis,
> the energy does come from the person, but was
> temporarily stored in the
> wall.  There will also be dissipative losses, but we
> can imagine those being
> minimized.
>
> If the above isn't complete nonsense, then there
> seems to be some
> pedagogical advantages in maintaining a single WE
> approach.  I'm not really
> against John's emphasis on momentum transfer, but
> I'm having trouble with
> the mechanism by which the energy stored as chemical
> PE ultimately becomes
> KE of the CM through only internal conversions.
>
> Rick
>
> ----- Original Message -----
> From: "Rick Tarara" <rtarara@saintmarys.edu>
> To: <PHYS-L@lists.nau.edu>
> Sent: Wednesday, February 06, 2002 10:15 AM
> Subject: Re: car acceleration
>
>
> > Of course one might muddy the waters some more by
> considering that if the
> > wall is _really_ rigid and is really rigidly
> attached to the earth, then
> the
> > push changes the rotational velocity and the
> rotational KE of the earth,
> but
> > I won't go there!   ;-)
> >
> > Rick
> .


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