Questions tagged [reversibility]

The potential for a thermodynamic process to be reversed in time. Alternatively, a quantification of how far an irreversible process is from being reversible, which relies on a comparison to a corresponding theoretical reversible process.

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Can I assume that steam leaking from a rigid insulated tank is an isentropic process?

I’m trying to solve this problem. If you have a rigid insulated tank with $V=10\ {\rm m}^3$ which is initially filled with steam at $p_1=0.7\ {\rm MPa}$ and $T_1=240\ {\rm C}^\circ$. The tank develops ...
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Can a non-unitary free operation on a resource state be reversed?

Under the framework of resource theories like entanglement, asymmetry, athermaility, etc, a set of operations $\mathcal{O} \subset \mathcal{B}(\mathcal{H})$ is chosen (e.g., LOCC) due to physical ...
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Big crunch theory

We study in thermal physics that no natural processes are reversible i. e. they are irreversible, so size of universe, it's also natural process. Why we still say big crunch theory a theory, why can't ...
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General definition of reversible process without mentioning changes in the environment

I'm looking a general definition of a reversible process for a (closed) system that wouldn't need to say anything about the environment and would be based on the intuitive notion of "reversing&...
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Reversibility of Physical Process : QM vs CM

It is often stated that the processes in quantum mechanics are reversible as they follow the Schrodinger's Equation : $$ - \frac{\hbar^2}{2m} \nabla^2 \Psi(x,t) + V(x,t)\ \Psi(x,t) = i \hbar\ \frac{\...
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Definition of reversibility for a non-adiabatic process

I would like to find a clear definition for the following expression: System A undergoes a reversible transformation when the transformation is not adiabatic (when system $A$ is not thermally ...
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Is a constant pressure adiabatic irreversible expansion possible?

We know that adiabatic law for an ideal gas is, $$ PV^{\gamma} =C$$ the differential of this under constant pressure is, $$ P \gamma V^{\gamma-1} dV = 0$$ Now, the pressure and volume can't be at all ...
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What features do reversible work have over the irreversible kind?

At 6:47 of this video lecture, the professor defines enthalpy for a constant pressure process as $$ q_{p}= \Delta U + p \Delta V$$ but, I can not understand why the work he implicitly starts referring ...
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What dependence does reversibility have on the time taken to change state of a system?

In this video lecture , at 39:37, The professor describes that if we do the process slowly then the system moves through a set of equilibrium states but why exactly does the speed of doing the process ...
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Two Polytropic and Two Adiabtic processes in Thermodynamic cycle [closed]

$1$ mole of an Ideal gas performs a reversible cycle with 2 adiabatic and 2 polytropic processes. $A(P_0,V_0,T_0)$ to $B$ with $V_B=V_A/\lambda$ with an adiabatic process. $B$ to $C$ with a polytropic ...
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Are irreversibility and unpredictability in a system caused by the huge number of molecules?

In my understanding, if we imagine two molecules in a system, we can predict what's going to happen and it's easier to reverse the process than to predict the motions of billions of molecules and ...
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Do irreversibilites change the final temperatures of two bodies?

When two identical bodies are brought into thermal contact, and both are surrounded by an isolation, does the fact that they have a finite temperature difference, which generates entropy, change their ...
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Why are simple models of coupled pendulums incapable of describing irreversible energy dissipation?

Consider two pendulums $A$ and $B$ coupled by a spring and also regard $A+B$ to be a completely isolated system. Let us start the system in an initial configuration where only one of the pendulums (...
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Why is the work done in reversible process greater than work done in irreversible process?

I have read in my textbook that maximum work is done by gas in a reversible expansion, but I do not know the reason behind it. Also is work done by gas maximum in reversible compression also?
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Examples of processes that are reversible isentropic but not adiabatic?

Since $ds=\frac{dq_{rev}}{T}$ for reversible processes it seems we can have reversible isentropic processes that are not adiabatic provided the temperature changes in such way that the sum of $\frac{...
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How does the reversibility of physics interact with nuclear fission?

The laws of physics are reversible and quantum information is never destroyed. Given this, how do I time reverse the $U_{235}$ fission reaction, n which ${}^1_0n + {}^{235}_{92}U \rightarrow {}^{141}_{...
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How to find the maximum work that can be extracted by two objects which have variable temperatures?

How to find the maximum work that can be extracted by two objects which have variable temperatures $T_1$ and $T_2$ with $T_1 > T_2$? I've thought that the maximum work obtainable is the one ...
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Conditions for a process to be quasistatic, non-quasistatic, reversible or irreversible

I have a little mess with the conditions required in thermodynamics for a certain process to be quasistatic, non-quasistatic, reversible or irreversible. Let's start with the classification of the ...
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Why the reversibility requirement in Clausius equality doesn't prevent defining the entropy from it?

In his original work Clausius defines the entropy from his equality $\oint \frac{\delta Q}{T}=0$, which holds for a reversible cyclic process. As it means the integral $\int \frac{\delta Q}{T}$ over a ...
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Obtaining the direction of flow from principle of increase of entropy?

Can we mathematically show that water flows from high-pressure region to low-temperature region and why particles flow from a region of higher chemical potential to lower on the basis of the principle ...
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Isothermal Irreversible process

I'm in high school and wanted to get a few things cleared up. Isothermal process is defined as a thermodynamic process where temperature remains constant. Does this mean that temperature remains ...
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Does first law contradicts 2nd law of themodynamics?

We can write first law of thermodynamics in two forms. $$dU=TdS-pdV$$ and $$dU=dq+dw$$ It is also true that $dw=-pdV$ therefore $TdS=dq$ for every process irrespective of reversibility. What I am ...
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Kullback-Leibler divergence as a measure of irreversibilty?

I watched this recent KITP webinar on Nonequilibrium thermodynamics for active matter yesterday. I saw that KLD(Kullback-Leibler divergence) is used as a measure to quantify irreversibility in the ...
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Why is the speed of a process related to how irreversible it is?

Almost any physics major is taught that By an infinitely slow process, one can change the state of a system from A to B in an irreversible manner. Normally, the above explanation is accompanied by ...
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How to prove the existence of a certain thermodynamic path between two points?

Suppose I have two points on a PV graph labeled as A and B both having same pressures (that is the process is isobaric) and the volume of A is less than that at B. How can we rigorously prove that ...
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Difference between reversible and irreversible heat transfer

Reference books define reversible heat transfer as heat transfer occurs across a infinitesimal thermal gradient i.e. dT and irreversible heat transfer as heat transfer across finite thermal gradient i....
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Can you plot irreversible but quasi static processes on a $pV$ diagram?

I've often heard that you can't plot irreversible processes on a $pV$ diagram, but what about in the case where you have a quasi static process with friction? There still exists a curve of ...
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What is reversible heat?

If found the following question while studying thermodynamics. What is meant by "reversible heat" and when would it be a thermodynamic property (and when it wouldn't). I am not asking for the ...
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Irreversible isothermal compression of a gas increases internal energy? (Thermodynamics)

This is what I know: A reversible process is a process which occurs infinitesimally slowly. If you're isothermally compressing a gas infinitesimally slowly, the walls of the container decrease (...
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What is the physical interpretation of the Helmholtz free energy for an isothermic, irreversible process?

$$dF=-SdT-pdV$$ For an isotherm, $dF=-pdV$, so $\Delta F=-\int^{V_1}_{V_2}pdV$. Thus, a change in the free energy tells us how much work has been done by or on the system. However, at this point the ...
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Help with 2nd Law and irreversibilty [closed]

This question is about the seemingly idealized notion of isolated systems and truly irreversible processes in the context of the 2nd Law. Here are the definitions and citations I'll use then my ...
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Entropy as a state function for irreversible paths

Searching Physics Stackexchange for entropy I have found several posts regarding entropy, lately most of the questions why entropy is a state variable. This got me thinking. I have understood so far ...
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When differential of $p$-$V$ $dW$ work equals $-pdV$?

The differential form of the first law takes the form $$dU=\delta Q + \delta W$$ or $$dU=TdS-pdV.$$ First, we know that $TdS=\delta Q$ for reversible process. So we can't say that $dU=\delta Q -pdV$. ...
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Entropy generation at the molecular level in a irreversible process

When we expand an gas irreversibly in an adiabatic process then there is intermolecular friction, but what exactly gets transferred to heat. I have read that the directed motion gets randomized. But ...
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$\oint{A}=0\implies$ A is a State function?

If $A$ is a thermodynamic variable (ex:Pressure, volume, entropy). then If $\oint{A}=0$, then does it imply that $A$ has to be a state function? I'm trying to prove that Entropy is a state function. ...
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Proof for $\oint \frac{dQ}{T}=0 $ in a reversible process

I'm actually trying to prove that Entropy is a state function. I get struck at the point where I need to prove that $\oint \frac{dQ}{T}=0 $ for a reversible process. Clausius in his book The ...
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Entropy change in a reversible and Irreversible path

Let's consider 2 cases. First where a system is taken from state 1 to 2 in a reversible path. Second where the same system is taken from state 1 to 2 in an irreversible path. Can we say that Entropy ...
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How to formalize taking line integral by a reversible or irreversible path?

In thermodynamics work can be done by moving alone a reversible or irreversible path. Physical definitions of reversible and irreversible processes is uncommon in thermodynamics textbooks. The main ...
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Free expansion of interacting electron gas is an irreversible process

Consider a number of electron in vacuum, confined in a bounded region. These electrons have interaction described by QED. At $t=0$, we allowed the system to evolve. Without doing any measurement on ...
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How does the author identifies the irreversible process coming from the pressure difference?

In the book of Prigogine, Modern Thermodynamics, at page 113, it is given the example of an irreversible expansion of a gas. In a reversible expansion of a gas, the pressure of the gas and that ...
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Would entropy maximized at equilibrium if there were no irreversible processes? [closed]

I have read this question, but it does not answer my question: In a truly ideal isolated system (say an ideal gas), it is quite possible that there is no irreversible process such that the net ...
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How should I interpret this thermodynamic inequality?

I'm a little bit confused over the following inequality: $$ dS > \frac{\delta Q_{irrev}}{T} $$ An infinitesimal change in entropy is defined in this way: $$ dS = \frac{\delta Q_{rev}}{T} $$ ...
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What does Max Planck mean by this quote?

It is quoted in Prigogine Modern thermodynamics at the page 105 from Max Planck that Whether reversible processes exist in nature or not, is not a priori evident or demonstrable.’ However, ...
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Hysteresis of a ferromagnetic material and reversibility

Suppose a virgin unmagnetized ferromagnetic sample is magnetized to complete saturation. Usually, when we reverse the magnetic field, the system does not retrace its path in the M-H plane and there is ...
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Heating of Water, Reversible/irrevserible process

I'm hoping that someone can help me understand this problem. I am determining which of these processes are reversible and irreversible. If we had some beaker of water at room temperature which came in ...
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Is it possible to deduce the second law of thermodynamics from the first?

Considering the First law of thermodynamics as an axiom dU=dQ-pdV for any infinitesimal process, we should be able to prove that for any reversible(quasistatic) and cyclic transformation, there is at ...
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Reversibility of equation $F=mv$ [duplicate]

Please read the following text. This text is part of Leonardo Sauskind's book. It says that the relation F = m v is reversible. Why?
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Reversibility of the rules of classical mechanics [closed]

In the book of classical mechanics, Leonard Susskind says that Aristotle's equation of motion (F = mv) is reversible. But in the second lecture Theoretical Minimum 'videos say that F = mv is not ...
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Does entropy depend on reversibility?

When going through a cycle of a process $A \rightarrow B \rightarrow A$, is the change in the entropy of the system always equal to $0$? Does the reversibility of the process change anything (done ...
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Is it possible for matter to occupy a singularity, which is the point of rupture of space time caused by a black hole?

Also, are singularities caused by blackholes reversible? May one do work to reverse the singularity or black hole? Do blackholes create permanent holes in space time, thereby shrinking space time, or ...

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