Questions tagged [adiabatic]

Thermodynamic processes that occur without exchanging heat between the system and its environment.

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Work done in adiabatic process

When we try to establish a relation between the pressure and temperature in adiabatic process we come across a equation.. $dU = dq - PdV$ $dq=0$ (Adiabatic process) and, $dU=C_v.dT$ (Heat capacity ...
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Formula for molar specific heat capacity in polytropic process

I found this formula for a polytropic process, defined by $PV^n = {\rm constant}$, in a book: $$C = \frac R{\gamma-1} + \frac R{1-n} $$ where $C$ is molar specific heat and $\gamma$ is adiabatic ...
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The notion of an adiabatic process in thermodynamics -vs- quantum mechanics

I'm confused about the terminology in the two contexts since I can't figure out if they have a similar motivation. Afaik, the definitions state that quantum processes should be very slow to be called ...
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Adiabatic Quantum Computing: why not just set the system in its problem Hamiltonian $H_{P}$ immediately?

Background: In any adiabatic quantum computer (AQC) algorithm, we solve problems in the following manner: We have an initial Hamiltonian, $H_{0}$, whose ground state is easy to find, and a problem ...
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How is this process not quasi-static yet reversible?

Consider a (adiabatic) canister with a piston containing some gas kept in a vacuum. There are two weights on the canister which equalize the pressure of the gas on the piston. Assume the system is at ...
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Isentropic processes

I'm having trouble understanding why reversible adiabatic processes are isentropic. I understand that in a reversible adiabatic process there is no heat exchange and so $dQ = TdS = 0.$ However, if ...
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How do you explain the fact that when air expands freely into an evacuated chamber from a constant pressure atmosphere, its temperature increases?

I came across this paper: Baker, B. (1999). An easy to perform but often counterintuitive demonstration of gas expansion. American Journal of Physics, 67(8), 712-713. http://scitation.aip.org/...
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What is the difference between reversible and irreversible adiabatic expansion?

What is the difference between reversible and irreversible adiabatic expansion? Is it true that the work done by the gas is the same but the pressure applied externally differ between two process? ...
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Speed of a process in thermodynamics

As per my understanding, all adiabatic processes carried out in absence of an adiabatic wall need to be fast enough so that there is no heat exchange with the surrounding. Similarly, all isothermal ...
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Adiabatic theorem and Berry phase

As far as I can check, the adiabatic theorem in quantum mechanics can be proven exactly when there is no crossing between (pseudo-)time-evolved energy levels. To be a little bit more explicit, one ...
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Why does a gas get hot when suddenly compressed? What is happening at the molecular level?

My guess is that the molecules of gas all have the same speed as before, but now there are much more collisions per unit area onto the thermometer, thus making the thermometer read a higher ...
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How slow is a reversible adiabatic expansion of an ideal gas?

A truly reversible thermodynamic process needs to be infinitesimally displaced from equilibrium at all times and therefore takes infinite time to complete. However, if I execute the process slowly, I ...
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Adiabatic expansion in van der Waals gas [closed]

Given a Van der Waals gas with state equation: $$\left( P+\frac{N^2 a}{V^2}\right)\left( V-Nb \right)=NkT,$$ show that the equation of an adiabatic process is: $$\left( V-Nb\right)T^{C_V}=\text{...
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A question about the energy of turning on and off interaction adiabatically in QFT

I read a saying as follows: In a theory with no particles which decay and no bound states, the turning on and off of the interactions merely serves to limit the effective range of forces. In this ...
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Are reversible adiabatic processes always isentropic?

If my understanding is correct, neither reversible nor adiabatic processes are necessarily isentropic. But are reversible adiabatic processes always isentropic?
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Why is $PV^\gamma$ constant in an adiabatic process?

In non isolated systems where there is no adiabatic process, $PV$ is constant. But the graph gets steeper in adiabatic process because of the $\gamma$ over the $V$. Why is it there in adiabatic ...
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Why doesn't reversible adiabatic expansion generate heat?

In analogy to a compressed gas allowed to reversibly expand and do work, I've been thinking about the behavior of a compressed spring that is very slowly and incrementally relieved of its pressure. ...
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How to understand the indeterminate process in thermodynamics?

Consider a closed composite system with an internal movable adiabatic wall. If we release the piston, thermodynamics cannot determine the final equilibrium state (the temperature cannot be determined)....
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Are stationary quantum states attractors?

While explaining the quantum adiabatic theorem recently, I appealed to a thermodynamic analogy: when slowly contracting the walls containing a classical gas, the relaxation timescale can be taken to ...
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Is there relation between adiabatic process and electron degeneracy pressure?

Electron degeneracy pressure scales with density as: eq.1.1: $p \approx \rho^{5/3}$ By dividing electron degeneracy pressures of 1 mole of electrons at two different densities we obtain: eq.1.2 ...
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Adiabatic process of an ideal gas derivation

I am working through the derivation of an adiabatic process of an ideal gas $pV^{\gamma}$ and I can't see how to go from one step to the next. Here is my derivation so far which I understand: $$dE=...
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Change in entropy of two isolated systems merged into one system

From Statistical Physics, 2nd Edition by F. Mandl: Two vessels contain the same number $N$ molecules of the same perfect gas. Initially the two vessels are isolated from each other, the gases being ...
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Does “IF isentropic THEN reversible” only holds for adiabatic processes?

I know that: IF adiabatic and reversible THEN isentropic First question: does the implication IF isentropic THEN reversible hold for adiabatic processes? Second Question: if yes to the above, are ...
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Are sound waves adiabatic or isothermal?

I am doing a presentation on sound waves and I need to know if they are adiabatic or isothermal. I know that they can generate heat, but is the amount of heat created so small that it can still be ...
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Queries of proof of adiabatic theorem in QM

I have a few questions regarding the proof of the adiabatic theorem in the book "Introduction to Quantum Mechanics" by Griffiths: The assumptions are that if the Hamiltonian changes with time then ...
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Why is $dE = C_V dT$ for an ideal gas, even when the process is not constant volume? [duplicate]

I have come across the following derivation for the "equation of an adiabat for an ideal gas" in many textbooks. The following steps are referenced from a separate question: dE=dQ+dW dW=−pdV dQ=0 ...