Re: why pseudowork (NOT)

[Bob Sciamanda <trebor@VELOCITY.NET>]

Yes, Jim.  This is why I say that when you push off from a stationary
wall, the wall does work, even though the resulting energy of bulk motion
came only from internal sources, not from the wall!

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: Jim Green <JMGreen@SISNA.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, October 29, 1999 5:01 AM
Subject: Re: why pseudowork (NOT)


> > I would say, for instance, that when two blocks collide
> > inelastically, they may or may not do work on each other
> > (depending on the definition you want to use, the reference frame,
> > etc.), but they *certainly* do not heat each other (beyond some
> > minor amount that might occur by conduction simply due to
> > contact.)  Still, their internal energies increase and their
> > temperatures may rise measurably primarily as a result of the
> > conversion of bulk kinetic energy into internal energy.
>
> This seems to me like just so many words.  The _only_ way to increase
the
> internal energy of a system is to do either work or heat on the
> system.  (ie delta E = W + Q)  To say things like
>
> > conversion of bulk kinetic energy into internal energy.
>
> is just hand waving.
>
> We have already discussed ad nausium the fact that energy does not
> "move".  The only way to change the bulk kinetic energy is to do work on
> the system.  Why do we have to make such a mystery out of the First Law
and
> it's partner The Work/Energy principle.
>
> Jim Green
> mailto:JMGreen@sisna.com
> http://users.sisna.com/jmgreen