Re: Work/Energy Theorem

[Jim Green <JMGreen@sisna.com>]

John Mallincrodt has reminded me of his (w/ Harvey Leff) paper "All about
Work" AJP Apr92 p356ff.  It will take me some time to review this well
written work. In the meantime, let me ask some further advice:

At 05:41 PM 3/11/97 -0500, Gene Mosca wrote:

> > Can the kinetic energy of an object/system change if no work is done
> > to/by the object/system? 
>
> It sure can.  Imagine standing still on a frictionless surface and then
> pushing off a wall to get yourself moving.  Since the points of
> application of either the force on you or the force on the wall do not
> move, no work is done either on or by you.  However, you do gain kinetic
> energy as you slide away from the wall. 

OK, I see.  But let me probe how the *language* should be used: If a stick
of dynamite at rest blows and stuff flies all about, are we as a group
comfortable saying that no work was done?  I really don't have a firm
position here.  How about the list???   Or a system of two particles
connected by a compressed spring is freed???  No work???  [John, this is the
reverse of your example A]  In Gene's example above,  no work??? Really???
I will use any language agreed upon here, just tell me how to talk. (:-)











Jim Green
JMGreen@sisna.com