Questions tagged [thermodynamics]
Covers the study of (primarily homogeneous) macroscopic systems from a heat/energy/entropy point of view. Consider also using the tag: [statistical-mechanics].
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Should Callen's derivation about energy minimun principle care about the case that the extremum condition can't be achieve?
Callen's Postulate II says
The values assumed by the extensive parameters in the absence of an internal constraint are those that maximize the entropy over the manifold of constrained equilibrium ...
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A simple picture for the temperature vs density curve?
Consider $N$ particles interacting through a 6-12 Lennard-Jones pair potential (defined with particle radius $\sigma$ and energy barrier $\epsilon$) within a closed volume $V$ and evolving with ...
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Calculating the Bekenstein-Hawking entropy for 1+1 black hole with dilaton background
According to this paper the Bekenstein-Hawking entropy of a 1+1 black hole which described by the $SL_k(2,\mathbb{R})/U(1)$ WZW cigar geometry is given by the following formula appearing in eq. (5.7):
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Ising model in three dimensions
Which book or research paper has partition function estimates of three-dimensional nearest neighbor Ising model when the external field is zero?
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Thermodynamics of supersymmetric black hole
For a 4-dimenstional supersymmetric Kerr Newman black hole, we have
$$\beta\Omega=2\pi i$$,
and the index
$$\text{Tr}[(-)^Fe^{-\beta(M-Q)}]=e^{S+\beta\Omega J}$$
with $S+\beta\Omega J$ being $\beta$ ...
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Does squeezing a tea bag in hot water change the flavor? [closed]
This is a discussion I was having with a friend:
Its very likely that the temperature of the water you place a tea bag in while change the flavor of the tea (although I don't know why exactly from a ...
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Thermodynamics, states and path functions [closed]
How can we intuitively tell that if something is a state function or a path function, I tried searching it but I didn't get it clear. I got the analogy about the elevator and the stairs. But i need,
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Thermodynamics and Gibbs energy
The equation for the Gibbs free energy is: $\Delta G = \Delta H - T\Delta S.$
$\Delta H$ is the amount of energy difference between the initial state (characterized by $U_{i}$, $S_{i}$, and $V_{i}$) ...
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What happens if Torricelli Experiment used water vapour inside the tube instead of created a vacuum? [closed]
Recently i got experiment task for torricelli barometer, we know that when used water in vacuum tube, the water will rise up around 10 meter. but, i got curious and give a water vapour inside the tube....
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Thermodynamics and entropy
In a thermodynamics process, when heat is exchanged ($\Delta H$), it causes a change of system from state 1 to state 2. As a result, the entropy of a system is changed irreversibly.
Can the change in ...
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Application of first law of thermodynamics in the case of dipole inside an uniform electric field
I was solving a question. But am not able to properly grab the concept within it. It is related to dipole within an uniform eletric field. I'm not instrested in the answer [it's not a homework ...
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How do we get this formula for specific heat? Which process and conditions is this formula for? [closed]
Found this formula being used in a polytropic process where pressure was not even constant. So how are we finding specific heat for constant pressure? k in this example was the power in the polytropic ...
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Motion of Pressure Propelled Box
The problem is this: Suppose there is a rigid box with known volume V in deep space that has an extremely pressurized gas inside of it (known pressure p), at some known initial temperature T, with ...
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Why do phase changes have to be isothermal processes?
I was wondering if someone can explain simply why phase changes are isothermal processes?
I am studying hydrology and some of our material about snowmelt has to do with phase changes and in this ...
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Reversibility of the ideal Carnot cycle
How do adiabatic processes in the reversible Carnot cycle take place? Is the gas adiabatically isolated? If so, how would that happen in real life? (I know that Carnot cycle is not practically ...
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Thermodynamics and Special Relativity [closed]
What happens to the temperature of a body (not in the body frame) as it approaches the speed of light? My thinking is that the molecules will necessarily 'prefer' (as a natural consequence of the ...
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Frost on my windshield at 40° f on a clear cold still morning?
I LOVE this question/idea. So, how many different kinds of heating and cooling are there? If the "radiative" cooling or temperature of a clear night sky can be minus 60, how come I'm not ...
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How come the pressure gradient is equal to the divergence of pressure in incompressible fluids?
The net force due to pressure on a surface can be calculated by integrating the pressure over the surface. The equation for the surface integral of pressure is:
$$\vec{F} = \iint_S p\hat{n} dS$$
where ...
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How to find partition function of the system of particles having magnetic moment μ placed in a magnetic field B and particles obey M-B Statistics?
Here we get two energy levels uB and -uB which are discrete, but particles follow MB stats, it means there energy is continuous. I am getting confused, what is the role of the MB stats in such a case?
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In statistical mechanics, why is one "allowed" to treat classical systems probabilistically?
Is the essential argument that these systems are microscopically chaotic enough that we can approximate their evolution as random (vastly simplifying calculations) and still make accurate experimental ...
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Calculating temperature when it is lower than your thermometers can read?
We have an old freezer. I believe the thermostat is broken and think it may run all the time. Food in it gets really cold (Ice cream like concrete). I've tried measuring the temp with a freezer ...
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How can power be defined as the derivative of work with respect to time if work is not a function?
In thermodynamics, it is frequently said that work and heat are path functions with inexact differentials $\delta Q$, $\delta W$, so one can not talk about a change in work or a change in heat since ...
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Planck's assumption on blackbody radiation
I have just started basic quantum mechanics and have come across this expression for energy density of blackbody radiations; Planck's formulation.
$$ u_{\nu} \ d\nu = g(\nu) \ \langle E \rangle \ d\nu
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Marangoni effect and surface tension gradients in binary liquid
I have a question regarding the understanding of the Marangoni effect. A simple visualization is the deposition of a drop of soap (some surfactant-laden solution) into pure water. Because the soap ...
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A Jet of Steam passed into a Block of Ice
A jet of steam at 100 degrees Centigrade is passed through an orifice drilled in a 2 kilogram cubic block of ice at 0 degrees Centigrade. After some time, the ice fully melts. Calculate the mass of ...
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Second Law of Thermodynamics and heat flow
So I'm confused with The Second Law of Thermodynamics.
It says that heat flows from the high temperature to low temperature. For example, if we put a glass of cold water on the dining room, the cold ...
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Efficiency questions in a closed loop expander
So let's say I have a condenser, and both the inlet and outlet are connected to a pressure vessel that has hot gas fluid. Let's say there is a pneumatic pump creating a load on the connection to the ...
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Does the coefficient of friction (both static and kinetic) varies on prolonged application of friction forces?
Consider an example. Coefficient of Static Friction for a Pair of Materials for example Rubber tire and dry concrete road is 1.0 as per the data from my academic references. This coefficient of ...
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Zeroth Law of Thermodynamics on Thermometer
I'm confused by how thermometer works based on The Zeroth Law of Thermodynamics. The Zeroth Law of Thermodynamics said that
"If a body, A, be in thermal equilibrium with two other bodies, B and ...
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In this Stirling Engine process, how do we know that the fluid is heating up?
Since the volume of fluid in contact with the cold source and hot source is the same, how do we know the fluid is heating up instead of cooling down?
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Which method of heat transfer is faster? Convection or Conduction? [closed]
True or false question!
Conduction is the slowest mode of heat transfer - true (given in internet)
Now my question is, let's say you want to boil some water, in this case should not be the conduction ...
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Interpretation of non-spontaneous Gibbs free energy
Good day guys,
I was reading some books on physical thermodynamics, they explain that for system undergoing a chemical reaction whose $\Delta G < 0$ indicating that the reaction can then provide us ...
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The connection between entropy in physics and information theory [duplicate]
In physics, there is a version entropy which is defined as $S = k_B \ln W$ while in information theory it is defined as $H(X) = -\sum_{x} p(x) \log p(x)$. Why does entropy have different units in ...
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How to compute solvent reorganization energy in Marcus' non-equilibrium approach? [closed]
I try to solve the following equations for some system solvated in the water. The goal is to obtain value in kcal/mol. Unfortunately, I cannot reach the desired output. May someone help me?
The ...
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Is the speed of a single gas molecule in a box moderated (is the Maxwell Boltzmann curve narrowed)?
I see the second law of thermodynamics
as an observed law, not an imposed law:
it is broken sometimes on a larger scale
and broken often on a molecular scale.
So, if a box contains only one gas ...
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Assumption that work done by adiabatic process only depends on initial and final temperature, Rational Thermodynamics
I'm going through Rational Thermodynamics by C. Truesdell (2nd ed.) and in Appendix 1 (p. 89) he is deriving the constitutive relations between the pressure function $\bar\omega(V,\theta)$, the ...
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Clausius inequality and negative value of entropy [closed]
I was wondering...if entropy is a "state function" then why does going through an irreversible cycle give a negative value for entropy (Clausius inequality), I know it might be due to the ...
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Can Isobaric compression increase the internal energy of an ideal gas?
When an ideal gas is compressed isobarically the given energy by the external source is let out as heat alongwith some more heat that comes from the decreement of internal energy.
My question is why ...
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Sum of two state functions is not path independent
I am trying to explain the different physical meanings of the various thermodynamic potentials (before resorting to Legendre transforms, and without making appeals to statistical mechanics) and I ...
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Steam from a cup of coffee
I observed that, in winter there is more visible steam from a cup of coffee than in summer. Is there any phenomenon taking place here.
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Internal energy differential from the Gibbs free energy
The Gibbs free energy is defined as
$$ G = U-TS+pV$$
It is also known that the chemical potential is the per-particle Gibbs free energy so:
$$ G=\mu N $$
Now, putting the two together we get
$$ U = TS ...
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Counting microstates - simple example with boxes
I am trying to understand how to count microstates.
E.g. I find this explanation very intuitive: https://phys.libretexts.org/Bookshelves/Thermodynamics_and_Statistical_Mechanics/Book%...
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Does electron have a temperature in the atom?
Please correct me if I am wrong. Electron is fundamental and is zero dimensional (probably made up of strings). Electron is bound to the nucleus. Electron in an atom has velocity and position which ...
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Constant shift in the Gibbs free energy
As far as I know, measurable thermodynamic properties (pressure, temperature, volume, etc.) all depend on derivatives of the thermodynamic potentials. For instance,
$$1/T= (\partial S / \partial E)_{V,...
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Photoelectric effect and heating an absorptive body
As we know, two bodies undergo radiative heat exchange due to each emitting a spectrum of light according to its temperature (blackbody radiation).
When one body is hotter than the other, it emits a ...
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Find the ideal gas law from the internal energy [closed]
I'm looking for a way on how to obtain the ideal gas law $PV=nRT$ by being given the internal energy $$U=U(S,V)=\alpha N k_b \left(\frac NV\right)^{2/3} e^{2S/(3Nk_b)}$$ I can find the pressure and ...
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How to model adiabatic lapse rate from first principles?
As a motivating example, consider that the grand canyon floor is ~11ºC warmer than the top. The dry adiabatic lapse rate of 9.8ºC/km, at the average depth of 1.2km deep, implies a 11.76ºC warmer floor ...
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Hamiltonian as a quadratic function [closed]
I’m reading R.K Pathria’s Statistical Mechanics, third edition, and I'm having trouble understanding eq. (8) in section 3.7.
It goes like this:
In many physical situations the Hamiltonian of the ...
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Confusion on Change in Entropy
Which of these statements is more accurate?
Entropy is a state variable, whose change between points a and b we can calculate assuming a reversible path between those points. For a reversible path ...
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What is an good book to study classical non-equilibrum thermodynamics? [duplicate]
I am a physics student who has just started my master's program and am taking a course on classical non-equilibrium thermodynamics. I am looking for a book that can help me learn this subject. Are ...