Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: CONSERVATION OF ENERGY



Yes, I am tired. But I must reply to Leigh point by point. Why? Because
I love intellectual debates. They stimulate thinking and give desire for
further learning. Summer time is good because more time is available but
many people are away.

On Mon, 14 Jul 1997 Leigh Palmer <palmer@sfu.ca> wrote:

1) Would you be happy with this statement of the first law:

"The change in the thermal energy of a system is the sum of
the heat that flows into it and that part of the work that
is done on it that does not appear as a change in the
kinetic energy of the center of mass of the system"

Yes, if you accept informal synonymes for thermal energy, such as random
energy, dancing energy, chaotic energy of molecules and atoms, etc. Just
for fun of teaching.

Question: When is the term "heat" defined in an introductory course and
how? I guess you would say Q=c*(m+M)*dT, in our example. I am
not sure this is appropriate but my amunition is exhausted.
I am waiting for help.
Question: How do you deal with work? More specifically, the work done by
frictional forces? Aren't your students already drilled (at the
time the first law is introduced) that work is force*distance?
This is the "single particle model" of work. Should work be
defined before energy? Or is it better to change the traditional
approach ("German way" ?) and introduce energy before work?

Unless somebody comes with new amunition I will be answering the previous,
longer, message of Leigh after the supper in the best way I can.

Ludwik Kowalski