Recent content by abcdefg10645

As in the title , I recently somehow want to learn differential form , but ,actually , I do not really know where I should start , or what books I should read .. So,can anyone recommend some useful books ?

Well,I cannot fully understand what the term "etc" mean , could you be more explicit , or can you just type the solution to this annoying question ? Thanks again if I get any reply~

When I studied the fluid dynamic , I saw a quite hard equation (typed in attached file) , I don't know how to prove it , maybe there's a somehow relationship between this eq with Gauss's Divergence Theorem ... Can anyone help me ?

What's "quality factor" in oscillation ? I want to know why and how it was defined ? Is it useful in some ways ?

Thank u ~ I can now fully understand the reason why entropy is additive by ur explaining steps by steps !

Using the integral to calculate the (delta)S "OF A SYSTEM" is to calculate the difference of entropy for a particular process , I want to ask why , for different systems , it can also be added ?

Ha ha~never mind ~I believe that were just some typos But , I cannot understand why entropy is additive ?

But for different systems , their temperature T may not be the same ! First Law sates that deltaQ=dU+deltaW We can only infer that deltaQ is additive ! Please consider my comment~ Thanks

But how do you know that "Entropy increase by volume. " Let me restate my question : How can ew know that entropy is an extensive quantity by its definition dS=\int(dQ/T)

Why entropy is an extensive quantity ?

What u mentioned contains three variables ~and I've seen such a case in the book I read... Suppose \vec{F}=P(x,y,z)\hat{i}+Q(x,y,z)\hat{j}+R(x,y,z)\hat{k} dT=P(x,y,z)dx+Q(x,y,z)dy+R(x,y,z)dz is exact if only if \vec{F}\bullet(\nabla\times\vec{F})=0 I'm now requesting for the case which...

We can use Green's theorem to understand why the Exact Differential Equation satisfy the conditions it should have ... How about a DE for more than two variables ? Eg.dF=P(x,y,z,w)dx+Q(x,y,z,w)dy+R(x,y,z,w)dz+S(x,y,z,w)dw IF the equation above is an Exact Differential Equation , what...

It's NOT a homework first ~ And I am not satisfied with the proof I saw before ~ The proof I saw is based on the commutative of a vector ~ I'm now seeking for a new proof which make sense!

How can we proved that the infinitesimal angular displacement is a vector mathematically ? Or~how can we prove that a non-infinitesimal angular displacement is not a vector ?

I want to study it myself recently ~but I don't know where to start ? Can anyone help me ? XD