Wednesday, April 2, 2008

Freshman Curriculum: Thermodynamics

The understanding of thermodynamics in terms of statistical mechanics is not much older that quantum mechanics, if you date QM to 1905 rather than 1925. I think this negatively affects how this subject matter is taught in physics, but also in chemistry.

A few quasi-rhetorical questions for an open thread:

Why do we start with "heat" instead of internal energy?

Can we change the name of "specific heat" to something that indicates it really originates in the internal structure of the material?

Will U, with its implication that internal energy is a potential energy, ever be replaced throughout the chemistry, physics, and engineering world ... rather than here and there when Eint gets used in a freshman textbook?

I'll add others when I think of them.


Anonymous said...

Wait, did I miss something? I was under te impression that specific heat was heat capacity for unit blah blah blah. Operationally, a normalization in analogy to the way that acceleration due to gravity is gravitational force per unit mass, electric potential vs electrostatic potential energy, and such.

Though I suppose it's better to get a second opinion now than when I'm teaching baby thermo in two weeks or so... Amazing how spotty an education can be, huh? I was in grad school before I'd ever had any stat mech, so chemical potential was lots of fun, let me tell you.

Doctor Pion said...

Except that specific heat is not something as fundamental as potential energy or potential. It is more like density.

My objection is to a nomenclature that predates by centuries the realization that matter is made up of atoms in motion, where "internal energy" consists of the kinetic energy and potential energy an object still has in its rest frame. (By the way, this makes mass energy just another form of internal energy, not something mysterious.)

My objection is to calling it "heat", when we are trying to make a distinction between what is intrinsic and changes with the state variable T (the state variable U) and something like Q that can also be due to work.

It is true that Q is what we first observed as cavepeople, but we no longer start physics with Aristotle's notion of inertia. What I don't know is if anyone has done research on this subject, or even thought of reforming it.