Paul J. Gans
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 Jul 2 awarded Yearling Jul 2 awarded Yearling Aug 17 answered Derivation of Pressure/Kinetic Therory problem involving hole in box Aug 15 answered Can a liquid shrink as something is dissolved into it? Jul 2 awarded Yearling Jun 17 answered Where did Schrödinger solve the radiating problem of Bohr's model? Jun 17 comment What is the deal with heat capacity? I'm sorry, the answer above is incomplete, but I timed out before I could fix it. what it should say is: Well, no. Almost all differentials are "inexact" and they are written with a "d" or a "$\partial$". And Q occurs in a number of thermodynamic equations such as the balance principle in the first law $dE = dQ - pdV$, which you have used above, and the definition of entropy. Further, the general definition of the heat capacity is $\partial Q/\partial T$ with the appropriate quantities held constant. Jun 17 comment What is the deal with heat capacity? Well, no. Almost all differentials are "inexact" and they are written with a "d" or a "$\partial$". And Q occurs in a number of thermodynamic equations such as the balance principle in the first law $dE = dQ - pdV$ and the definition of entropy. Further, the general definition of the heat capacity is $Jun 16 answered What is the deal with heat capacity? Jun 16 comment Can a object with constant acceleration change its trajectory? But wasn't the question about constant acceleration? Jun 6 comment How to reconcile the two definitions of work? (mechanical and thermodynamical) I do think you are making a mistake. The definition of infinitesimal work is unambiguously the dot product of the force vector and the infinitesimal distance vector. The mistake you are making is that the work is being done on (or done by) the WEIGHTS on the massless piston. I do not know what other definition of work one can use. We are not calculating the work done on or by the piston itself. Jun 6 comment Schrodinger's cat experiment The cat is not an observer for all the reasons already given plus the fact that the cat cannot communicate what it observes to us. So the cat can be ignored. But I repeat my statement above involving two sets of observers, one able to see the cat, the other not. For the observers that see the cat, there is no superposition. If the cat dies, a transition between the life and death states is seen. Otherwise the cat continues alive. The conclusion to all this is that the state function reflects the observer's knowledge and NOT necessarily objective reality. Jun 4 answered Why does the Boltzmann factor$e^{-E/kT}$seem to imply that lower energies are more likely? Jun 4 answered How to reconcile the two definitions of work? (mechanical and thermodynamical) May 21 answered Question about the proof that heat capacity goes to zero if temperature approaches$0K$May 20 answered Isothermal Gas Expansion, a Reversible or Irreversible process? May 10 comment Does the collapse of the wave function increase entropy of the atomic system itself? Unexplained downvotes ought to be forbidden. The person who answers sticks their necks out but the people who downvote get to be anonymous. Doesn't seem fair. May 4 answered What counts as “observation” in Schrödinger's Cat, and why are superpositions possible? Apr 26 comment How is it possible to equate the internal energy at constant volume with the internal energy of an adiabatic process? @joshphysics is quite right. I add two notes. One is that the resulting formula hold ONLY for ideal gases. The other is that in$w = -pdV$,$p\$ is the internal pressure ONLY if the process is reversible, because only then are the internal and external pressures equal. Apr 25 comment The notion of an adiabatic process in thermodynamics -vs- quantum mechanics I agree with @joshphysics. In chemistry it is unambiguous that "adiabatic" means "thermally isolated". Thus an explosion, at least in its initial stages, can be and is treated as adiabatic because there is not enough time to exchange much heat with the surroundings. Further, adiabatic processes do NOT have to be at or near equilibrium. Those paths are called "reversible". Adiabatic paths can be reversible but are not mandated to be such.