# Questions tagged [adiabatic]

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

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### Why isn't the free expansion of a gas in an adiabatic container isentropic?

If you expand a gas adiabatically using a piston, the process is isentropic. However, if you simply remove the piston and let the gas expand freely, the process is now not isentropic. What makes these ...
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### How does the adiabatic coefficient $γ$ vary with temperature (200K-20000K)? [closed]

At high temperatures, such as those encountered in hypersonic flight, γ varies a lot. My problem is that I can‘t find a graph accompanied by an explanation as to how & why it changes under ...
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### Adiabatic equation of state for a star

I am a little confused. To describe stars the adiabatic equation is often used: P = k$\rho^{\gamma}$. For a monatomic gas, the following holds: $\gamma = \frac{5}{3}$. However, since the sun is not ...
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### Adiabatic Transformations and ideal gas relations

For an adiabatic transformation of an ideal gas I know that from equation, $C_v=\frac{dU}{dT}$ I can rewrite it using the relations, $dU=dQ-dW$ which can give us $dU=-pdV$ to rewrite the first ...
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### Thermodynamic adiabatic process, question regarding mathematical operations

I have a question regarding mathematical operations often seen in physics books: In an adiabatic process the heat is 0, so by the first law of thermodynamics we have that $E = W$, and an infinitesimal ...
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### Proof of Caratheodory's theorem

Caratheodory's formulation of second law of thermodynamics, also referred to as Caratheodory's principle states In any neighbourhood of any thermodynamic state $P$ there exist states which are ...
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### Problem related to adiabatic invariants [closed]

A simple pendulum is oscillating in the gravity field, while its length slowly decreases with time. Determine amplitude of the small oscillations $A$ of the bob, when length of the oscillating part of ...
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### Understanding the use of $d$ and $\partial$ in thermodynamics

It seems a hundred variations of this question have been asked, and it's difficult to find which of those questions relates to exactly what I'm asking. My apologies if exactly this question has ...
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### Why is the value of the heat capacity ratio $\gamma$ never less than 1?

For an monoatomic gas, the value of the heat capacity ratio $\gamma$ is 1.67 For diatomic gases, the value of γ (gamma) is 1.40 For many atomic gases, the value of γ (gamma) is 1.33 It's never less ...
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### Question regarding using $dU=nC_vdT$

In an Adiabatic process ,$Q=0$ (heat added or removed from the system is 0). First law of thermodynamics states that , $dU=Q-W$...(1) $Q=0$ . Therefore $dU=-W$. Now my question is why $dU=nC_vdT$ used ...
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1 vote
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### Is an isentropic process always adiabatic? [duplicate]

I am making an exercise about a pulsating jet engine. There is a part in the cycle of this engine that is an isentropic expansion and i'm wondering if I can use $PV^{g} = cte$ in this process
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### Is adiabatic work extensive?

The First Law of Thermodynamics for an adiabatic process is: $\Delta U=W$. The internal energy is extensive. Thermodynamic work is neither extensive nor intensive in general, but is it extensive, if ...
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### What is the adiabatic temperature gradient of ice?

What is the adiabatic temperature gradient of ice at Earth's surface conditions? The adiabatic temperature gradient is a non-conductive spatial temperature difference caused by acceleration on thermal ...
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In this1 paper they use an adiabatic approximation to reduce two differential equations to one. Could you please recommend some alternative reading for this (semi) classical adiabatic approximation, ...
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### Uniqueness of Irreversible and adiabatic processes in finite time

Let the external intensive and extensive "mechanical" variables be denoted by $Y_k, X_k$. These variables are well defined irrespective of the system is in equilibrium or not. For an ...
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### Can adiabatic heat exchange between different temperatures ever be reversible?

I've been told, A volume 2X of Temperature 0.5*(T1+T2) is always at higher entropy than thermally insulated volumes, 'X' at T1, 'X' at T2 put together. Let's take Sys1 (A volume 2X of Temperature 0.5*(...
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### What steps are exact in Born-Oppenheimer and adiabatic approximation?

I am reading about adiabatic and Born-Oppenheimer approximation and I can't understand what steps are exact and what steps are approximations. Both these approximations are based on the idea that as ...
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### Adiabatic sound speed in static spherically-symmetric perfect-fluid solutions (SSSPF) of Einstein field equations (EFE)

Why $\sqrt{dp/d\rho}$ is interpreted in SSSPF solutions as adiabatic speed of sound although the corresponding equations are static? In static world all times derivatives are zero and without wave ...
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### Why adiabatic expansion happens in Carnot cycle

$A \rightarrow B$: Isothermal expansion happens. Since the internal energy purely depends on the temperature ($E_{int} = knRT$, $k = \frac{3}{2},\frac{5}{2},3$), then $\Delta E_{int}=0$ in an ...
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### Why the irreversible work carried in an adiabatic condition never causes change in internal energy?

I saw the lecture of thermodynamics on the MIT opencourse ware . In that lecture , the professor said that change in internal energy in an adiabtic process is caused by only reversible work , and not ...
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### Role of Berry's curvature in nanomaterials

what is the physics behind Berry's curvature? In many papers, they are explaining topological and anomalous quantum hall effects via Berry's curvature. but what is the physics behind this curvature ...
1 vote
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### Normal Shockwaves and its Thermodynamics

Please read this page before going to my question. When we derive the relation between Mach no. to the left side of the shock wave (M1) and that to the right side of the shock wave (M2),we do that ...
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### Adiabatic turn-on of free multi-particle states

Consider a second-quantized operator $\mathcal{H}_{full}$ describing some interacting QFT, whose action is known on a set of Fock states $\{\mathcal{|F\rangle}\}$, which, in turn, are the eigenstates ...
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