Re: work done by friction

[John Denker <jsd@MONMOUTH.COM>]

At 05:29 AM 10/27/99 -0800, John Mallinckrodt wrote:
> except
> under equally extrordinarily implausible scenarios, the table gains energy
> so, using the same logic, something *must* do positive work on it.

In the situation in question, nothing can do work on the table, since it
was stipulated to be stationary.  The table gains only heat.  The
frictional heating is not different in principle from shining a heat-lamp
on it.  According to any reasonable definition, this is heat not work.

I am making the traditional reasonable distinction between work (which
involves macroscopic organized motion) and heat (which involves microscopic
disorganized motion).

The fact that friction did negative work on the block does *not* imply that
something did positive work on the table.  Work is not conserved.  Energy
is conserved.

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