I can only say what I personally like and what I do.
First, I tell the students to be very careful about the sign of work because
different people view it oppositely. I tell them it is just a matter of
definition.
Second, I prefer the proposed definition. One might say I have this
preference because I first learned thermo as a chemist. However, at the
time I first learned thermo I was in college in the late 1960s. At that
time the chemists and physicists agreed. The current chemistry convention
came years later.
The reason I like work done on a system as positive is because I like that
the energy of the system increases when work is done on the system. That
seems more natural to me. If one system does work on another system, the
system doing the work has some form of energy going down, and the system
receiving the work has some form of energy going up. The new convention
makes the +/- signs the same for work and delta-E in each system. That
seems perfectly normal to me.
I suspect one problem people have with this involves the philosophy of the
work-energy theorem: w = +/- delta-E. If w and delta-E both apply to the
system, then we would be inclined to think w means work done by the system,
and we need the negative sign. If we think of w as work done on the system
then we need the positive sign... but then it might seem odd that the left
side describes something done to the system, and the right side involves
some property of the system.
I think the last sentence is important because it helps remind us that work
is not a property of the system. The equation is not relating one property
of the system to another property of the system. It is relating a property
of the system (right side) to an interaction between the system and the
surroundings (left side). In that light, I don't have any problem with, and
I actually prefer, that the left side represents something the surroundings
do to the system, and the right side represents how the system responds.
Again, this seems natural to me.
I vote for accepting the change.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817