All Questions
Tagged with reversibility thermodynamics
535 questions
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Difference in efficiency of isobaric reversible and irreversible process [closed]
I know that the efficiency of a process depends on the reversibility of the same process. When the process is reversible, the efficiency is the highest. Although I don't understand how this works for ...
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Irreversible Processes in Thermodynamics
Here’s the updated text using dollar signs for MathJax formatting instead of parentheses:
Question: Understanding Work in Irreversible Processes in Thermodynamics
I am currently studying irreversible ...
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Whats the lowest energy substance reaches during adiabatic expansion of carnot engine? [closed]
In carnot engine we know the steps like first isothermal, than adiabatic, then reverse isothermal and adiabatic.
And we know that efficiency increase if the temperature of hot box(heat supllier) is ...
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Confusion about reversibility of a carnot engine
I recently posted a question about entropy and the conversation changed topic to bring up an interesting question. @Chemomechanics explained that for a transformation to be reversible it is needed ...
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Equilibrium in a reversible process
My lecture notes state the following (albeit in a very hand-wavy way):
If we
are gentle and careful however, we can change the state of the system slowly, making sure that while
the state is changing ...
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Plotting reversible and internally reversible processes
I know that we cannot plot irreversible process on thermodynamic coordinates. So can we plot 'completely reversible' processes on thermodynamic coordinates, or just 'internally reversible' processes?
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Is an interaction-free measurement an irreversible process?
From what I've understood from reading different online sources including PSE*, measurements in quantum mechanics are generally argued to be irreversible (at least, when a macroscopic measuring device ...
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Entropy in a thermally isolated system
In page 141 of the book "Concepts in thermal physics" it is said that for a thermally isolated, the change in entropy is bigger or equal to 0 since $dQ=0$.
But since the system is thermally ...
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Derivation of 1st law of thermodynamics using microcanonical ensemble
In the book Statistical Physics of Particles by M. Kardar, the author shows the connection between the microcanonical ensemble and thermodynamics deriving the zeroth, 1st and 2nd laws. In the ...
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How is entropy a state variable, and how can we measure entropy from irreversible processes with reversible ones, from a Khan Academy video
My questions :
How is entropy a state variable?
Why can we use a reversible process to measure an irreversible process's change in entropy if irreversible processes generate extra (unaccounted for ...
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Difference between an internally reversible process and a totally reversible process
In Çengel and Boles, it is said that the area under a T-S diagram for an internally reversible process is equal to the total heat transfer during the process.
The example given of an internally ...
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Generalization of Heat input in a $pV$ curve for a reversible process
I was wondering, is there a way to generalize by just looking at a PV curve for a certain process that heat flows into it or out of?
For example, for a cyclic process if the process is "clockwise&...
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Why is rapid expansion/compression considered a reversible/isentropic process?
I am looking over the Otto Cycle on this MIT website and it says at one point "the processes from 1 to 2 and from 3 to 4 are isentropic" in reference to the expansion and compression of the ...
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Does bitcoin mining take work?
I'm neither a professional in cryptocurrency nor physics, but an interesting idea occurred to me. Bitcoin involves mining, which generates a lot of heat as waste.
Is the amount of heat produced by a ...
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Is interpreting information conservation as time reversibility non-mainstream physics?
I understand the following as standard results in modern physics.
Black holes evaporate over time via Hawking radiation.
Small black holes evaporate over very short times.
There is an "...
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Quasistatic and Reversible thermodynamic processes
A quasistatic process is a process where all intermediate states are in equilibrium. A reversible process is a process where no entropy (of the universe) is generated (and thus can be reversed to its ...
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How is a irreversible process (conventionally) represented on a $T-S$ plane and why cannot it be (really) represented?
A reversible process can be represented on a $T-S$ plane, and the area under the curve is the heat exchanged by the system.
On $P-V$ plane a irreversible process is conventionally represented with a ...
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Joule free expansion and differentials in irreversible processes
I am studying thermodynamics (undergraduate level) and I am not sure I understand what happens in irreversible processes.
I thought I understood but then I got confused in the Joule free expansion (...
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Derivation of reversible flow work for open systems
In derivation of steady reversible flow work, what sort of model are we considering, when we write the differential form of first law as $$\delta w=\delta q- dh-vdv - gdz $$
for one inflow and one ...
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Does Isobaric process imply quasi-static?
For a system that undergoes a process that takes place at atmospheric pressure, the work done by the gas can be expressed as $-P_{\rm atm}\mathrm{d}V$.
Does this mean that the process is always ...
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Adiabatic process and internal energy
My question concerns the connection between change in internal energy $dE = Q - W$ and the available work in an adiabatic process.
My understanding is, that in an adiabatic process ($Q=0$) the change ...
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Can the Efficiency of an Arbitrary Reversible Cycle be Equal to the Efficiency of the Enclosing Carnot Cycle?
I was reading the following article:
https://www.researchgate.net/publication/...
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The development of Clausius Inequality
The reversible cyclic device absorbs $\delta Q_R$ from the thermal reservoir at $T_R$ and rejects heat $\delta Q$ to the piston-cylinder device, whose temperature at that part of the boundary is $T$ (...
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Why is the entropy change for a system in irreversible transformations the same as in reversible transformations in some cases, not in other cases?
Generally, the entropy change for a closed system for an irreversible transformation is not the same in a closed system for a reversible transformation.
A clear counterexample is that of an adiabatic ...
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Why thermodynamic equilibrium and pressure balance is considered for having a reversible process? [duplicate]
When we compare the rapid expansion of an ideal gas to a very slow expansion from an initial state to a final state, we categorize one as irreversible and the other as reversible. This distinction ...
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Less loss of energy in reversible process
Why is there less loss of energy in reversible process?
I found this:
The reversible expansion does the maximum amount of work because the gas is pushing against the maximum possible external ...
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Reversible vs Quasistatic
I have some confusion about the definitions of a quasi-static and a reversible thermodynamic transformation.
As far as I understand, a quasi-static process is one that happens slowly enough for the ...
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2
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Clarification on 2nd law of thermodynamics
I was reading Feynman lectures on the 2nd law of thermodynamics
Now, what about the second law of thermodynamics? We know that if we do work against friction, say, the work lost to us is equal to the ...
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Can two different points can be connected by multiple adiabatic curves?
I was watching this Thermodynamics lecture and I have a question on the 1st law. More exactly on how different adiabatic curves can connect the same initial and final states. See the diagram drawn at ...
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What is the difference between two methods of calculating irreversible work in finite-time thermodynamics?
In finite-time thermodynamics, there are two methods for calculating irreversible work, derived from two different papers:
Method 1 (from doi: 10.1103/PhysRevE.104.034117):
Excess work: Work under ...
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Confusion regarding the equation $dS=\frac{\delta Q_{rev}}{T}$
In Reif's Fundamentals of Statistical and Thermal Physics he outlines a "proof" (sections 3.8 and 3.9) of the equation $dS=\frac{\delta Q}{T}$ for any quasi-static, infinitesimal process (i....
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Can ideal gas equation $PV = nRT$ be used in the intermediate stages of a irreversible and reversible process?
Suppose we have two processes, one is reversible and the other is irreversible. The ideal gas undergoes from state A to state B in both processes.
I want to know that can I apply the formula $PV = nRT$...
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Feasibility of entropy at zero temperature
I remember a college lecturer of mine once gave me this equation of entropy during one of his lectures on thermodynamics:
$$
\begin{align*}
\Delta{S} = \frac{ d {Q} }{T} \\
\end{align*}
$$
I found out ...
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Why a reversible engine's efficiency must be equal to that of a Carnot engine?
Apparently, in order to prove that an engine must be as efficient as a Carnot engine if reversible is because apparently for its efficiency in either direction:
$\eta_E \le (1-T_2/T_1)$
$\eta_R \ge (...
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Is the 2nd law a reason for the irreversibility of natural processes or a consequence of it?
I have been introduced to chemical engineering thermodynamics due to my academic background. I had learnt about internal energy, entropy etc and applied the equations to various scenarios of practical ...
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Why is heat transfer reversible when temperature difference is infinitesimal?
I don't understand why heat transfer from hot reservoir to the system is considered reversible in this case:
$T_{reservoir}$ = $T_{system}$ + dT
but it's considered irreversible in this case:
$T_{...
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Entropy in irreversible adiabtic process
We know that,
$$dS=\dfrac{\delta Q_{rev}}{T}$$
If you have an irreversible adiabatic process between two thermodynamic equilibrium end states of a system, there exists no possible reversible adiabatic ...
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Use of Clausius theorem to prove entropy inequality in Fermi's Thermodynamics
At the beginning of Section 13 (at the bottom half of page 54 through the top half of page 55) of Enrico Fermi's classic Thermodynamics, he sets out to prove the relation (using his notation)
$$S(B) - ...
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What is the relationship between Clausius Inequality and 2nd Law?
I am confused about the application of the 2nd Law for reversible and irreversible processes and cycles.
I want to know how the Clausius principle, the Kelvin-Planck statement, and the Clausius ...
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2
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What is the difference between a reversible process and an equilibrium? [closed]
I am confused about the differences between a reversible process and an equilibrium when considering their energy aspect.
Here is what I know so far.
(1) Equilibrium and Reversibility
Equilibrium ...
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1
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336
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Reversible vs Irreversible process
A Hypothetical Situation:
Two thermally isolated identical systems have heat capacities which vary as:
$$Cv =βT^4$$($β$ is constant)
Initially one system is at $300K$ and the other at $400K$. The ...
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Work done in adiabatic process irreversible and reversible
Work done for adiabatic reversible process is $$(P_1V_1 - P_2V_2)/(γ-1)$$ but this is also the work done for adiabatic irreversible process. How?
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Given a viably physical (isolated), quantum many body Hamiltonian, does an initial state of a superposition of energy eigenstates ever thermalize?
Given a viably physical, quantum many body Hamiltonian of a isolated system, if initially a state is prepared which is a superposition of energy eigenstates in an interval centered at E and E', not at ...
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Can equilibrium thermodynamics be used to analyze irreversible processes?
As usually taught in undergraduate courses, classical thermodynamics is actually thermo-statics, the thermal physics of equilibrium states. Even in this very restricted form it can and does make ...
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Is this a counterexample for the idea that reversible and quasi-static processes must infinitely slow?
Many people say that a reversible process must be quasi-static and infinitely slow. I (think I) understand the examples involving gases inside pistons to demonstrate the point, but I don't understand ...
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Distinguish a reversible process via measurements
Is it possible to distinguish between reversible and irreversible processes - say, the process of the working substance in a heat engine - via a measurement?
Its a bad question, in the sense that ...
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Change in entropy in reversible and irreversible process
Let's take a process with constant pressure in ideal gas for example. in reversible process
$dS=\int_{1}^{2}\frac{\delta Q_{rev}}{T}=\int_{1}^{2}\frac{C_pdT}{T}$
Assuming constant specific heat ...
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Why entropy change of reservoir is reversible?
When two reserviors exchange heat, it is considered as reversible heat transfer and entropy is calculated.
But when the process is reversible change in entropy of universe must be zero. But why ...
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Clarification on the Use of $\frac{dS}{dE} = \frac{1}{T}$ vs. $\frac{dS}{dQ} = \frac{1}{T}$ in Thermodynamics
I'm currently studying thermodynamics and have encountered two expressions relating changes in entropy to temperature, but applied in seemingly different contexts:
$\frac{dS}{dE} = \frac{1}{T}$, ...
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Why Onsager's formulation of thermoelectricity is better than Bridgman's?
General comment: despite the longish historical introduction this question is not about the history of physics but rather about a specific conceptual problem in physics.
Following Bridgman in the ...
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