Recent content by Jeremy1986

Thank vanhees71 for your kind reply! I think I start to understand the answer to my question as I wrote it in the reply to Lord Jestocost

Thank you very much for your excellent reply! Also many thanks to the provided useful references. I think I start to know the answer to my question after reading your reply. I think the key point is that equilibrium is a macroscopic property which we can't say a microscopic state is at...

Thank Michael for your kind reply! I think maybe my misunderstanding was that equilibrium does not correspond to microstate.

Thank mfb for your kind reply! I think maybe my misunderstanding was that equilibrium does not correspond to microstate.

In deducing the zeroth law of thermodynamics in micro-canonical ensemble, there is a frequently-mentioned example. Suppose we put two isolated system, system 1 and 2, in contact and allowing them to exchange heat. The total energy of the combined system is $$E = {E_1} + {E_2}$$ The total...

Thank you very much for your nice reply! I think I start to understand my first question. What I was puzzled is actually the difference between ##\frac{{d\rho }}{{dt}}## and ##\frac{{\partial \rho }}{{\partial t}}##, which I now realized defines change in ##\rho## along the path in phase space...

With the Liouville's theorem $$\frac{{d\rho }}{{dt}} = \frac{{\partial \rho }}{{\partial t}} + \sum\limits_{a = 1}^{3N} {(\frac{{\partial \rho }}{{\partial {p_a}}}\frac{{d{p_a}}}{{dt}} + \frac{{\partial \rho }}{{\partial {q_a}}}\frac{{d{q_a}}}{{dt}})} = 0$$ when we calculate the time evolution...

Thanks Prayaga, it really helps!

i think that maybe because the wave function u(x,t)=Acos[ω(t-x/v)+φ0] is the function of a wave that is steady in the space. so the derivation in the textbook gets the right wave function, but it is wrong to think like that.

Hi guys, Greetings! I have a confusion about the wave function of a traveling wave. This is the wave function of a traveling wave traveling towards the positive direction of x axis u(x,t)=Acos[ω(t-x/v)+φ0], where v is the velocity of the wave, ω is the angular...

Thanks PeroK! I was out for the past couple of days, and sorry for the late reply. your reply enlightens me, and i think you are right. as the statement in the question "The angular momentum of the ball is conserved with respect to the center O", we can get that f'θ in the disk-reference frame...

i got some idear after posting this thread :biggrin: the statement "A ball move with respect to the center of the disk in a trace of Archimedean spiral r=αθ," here 'with respect to' mean r andθ is in the disk reference of frame. the conservation of angular momentum can only happens in the...

Dear guys, Recently, i am confused with a problem in my textbook of mechanics. The question is, suppose there is a disk, placed horizontally, rotate about its center with angular velocity ω. A ball move with respect to the center of the disk in a trace of Archimedean spiral r=αθ. The angular...

so do you mean a solid is macroscopic translational invariant? if we translate it with some distance in macroscopic scale, that solid still stay as it just changed its position. can we call it macroscopic translational invariant? but translational invariant needs both macroscopic or microscopic...

with your kind help, i got better understanding of spatial correlation function. but i have a final puzzle, for solids or liquids, especially the amorphous solid, they use this kind of spatial correlation function, the so called pair distribution function. in the figure below, there is a...