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Jul
22
awarded  Yearling
Jul
22
comment Can ship/boat propellers be placed, with adequate protection, alongside the fuselage instead of at the back?
as for big aircrafts putting the engines on the wings is more convenient, because one can make modifications like changing fuselage length later more easily.
Jul
21
revised Introduction to differential forms in thermodynamics
added 100 characters in body
Jul
21
accepted Introduction to differential forms in thermodynamics
Jul
21
comment Introduction to differential forms in thermodynamics
That's indeed a nice point, it doesn't really worth introducing differential forms just for themselves. It would be worthy if such a formalism naturally incorporated in its structure the duality, conjugacy of thermodynamic variables. David has provided an example of this approach, but it is higher than an undergrad level and frankly speaking by this time I've never been actually meditating on this conjugacy. I really need to think it over, especially in the view of classical non-equllibrium thermodynamics.
Jul
19
comment Hamiltonian mechanics and special relativity?
@Qmechanic does it mean that the Hamiltonian equations themselves (the structure of phase space) doesn't change? Is the only thing that changes the allowed form of Hamiltonian? I couldn't find in Wikipedia anything about relativistic Hamiltonian mechanics itself.
Jul
19
asked Hamiltonian mechanics and special relativity?
Jul
19
comment Hamiltonian and the space-time structure
@Zhen Lin Classical physics has it's own space time, though quite special. And it defines the form of a Hamiltonian of a free particle (kinetic energy). As for the relativity theory, I just hoped that in such a manner I'll learn how Hamiltonian mechanics is generalized for that case. I'm curious about it either.
Jul
19
asked Hamiltonian and the space-time structure
Jul
18
answered Electricity takes the path of least resistance?
Jul
18
asked Introduction to differential forms in thermodynamics
Jul
11
revised List of Physical Toys
added 61 characters in body
Jul
11
revised List of Physical Toys
edited tags
Jul
11
awarded  Student
Jul
11
answered List of Physical Toys
Jul
11
answered List of Physical Toys
Jul
11
answered List of Physical Toys
Jul
11
asked List of Physical Toys
Jan
31
awarded  Commentator
Jan
31
comment Deriving an Expression for Entropy
The question is not how do you compute entropy (anyway one cannot generally compute the partition function), but how do you define entropy in statistical physics. I prefer the definition as $S = - \sum_i \; p_i \ln p_i$ ($- \int \rho \ln \rho \; d \Gamma$, $\text{Tr} \hat \rho \ln \hat \rho$). But following Boltzmann some use $\ln \Omega$ definition. I don't quite get that definition, at least in ensembles other than micro canonical. So I've asked how to derive one from the other partly because I wanted to understand that $\ln \Omega$ definition.