Questions tagged [adiabatic]

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

Filter by
Sorted by
Tagged with
5 votes
4 answers
905 views

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 ...
  • 642
0 votes
2 answers
28 views

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 ...
2 votes
0 answers
32 views

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 ...
  • 21
0 votes
0 answers
19 views

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 ...
0 votes
3 answers
54 views

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 ...
2 votes
1 answer
73 views

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 ...
0 votes
1 answer
27 views

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 ...
  • 35
3 votes
1 answer
79 views

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 ...
  • 51
3 votes
5 answers
106 views

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 ...
0 votes
2 answers
62 views

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 ...
1 vote
0 answers
22 views

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
0 votes
2 answers
73 views

What are the requirements to apply the Laplace Law in Thermodynamics ? Reversible and adiabatic, or just adiabatic?

The Laplace's Law in thermodynamics states that an adabatic reversible transformation of a perfect gas verifies the following identity : $$ PV^{\gamma} = cte \qquad \left( \gamma = \frac{C_p}{C_v} \...
1 vote
0 answers
30 views

Why is the action an adiabatic invariant in a unidimensional oscillator?

I'm reading Rax's "Méchanique Analytique" but I can't understand a particular step. We consider a unidimensional oscillator system with a potential that depends on a parameter $\lambda(t)$ ...
0 votes
3 answers
67 views

Entropy change during adiabatic expansion of ideal gas

I was told that the entropy change is $0$ during adiabatic expansion. However, according to $\mathrm dS=\frac{C}{T}\,\mathrm dT$, $\delta S$ is not zero because temperature is not constant during ...
  • 121
0 votes
0 answers
39 views

Adiabatic expansion and phase transition paradox

It is possible for a (real) gas to increase its temperature during adiabatic expansion and whether this happens it is strongly dependent on the intermolecular interactions of the gas. We can explain ...
1 vote
1 answer
23 views

Can I solve this problem using Gay Lussac's law of pressure? [closed]

This question came in the Khulna University admission exam 13-14 Q) When a tire is pumped at temperature $27^{\circ}C$, it bursts abruptly after its pressure becomes $2atm$. What is its final ...
2 votes
2 answers
76 views

Why don't we use the "degree of freedom" as a factor in the ideal gas equation?

For an adiabatic process, the ideal gas follows the equation $$ PV^{\gamma}= constant$$ The equation above implies that the pressure of an ideal gas (under adiabatic process) depends on the "...
  • 7,272
0 votes
0 answers
100 views

Comparing the final pressures/volumes/temperatures of a reversible and irreversible adiabatic process

Consider $2$ ideal and identical gases $A$ and $B$ which are at the same initial state of ($P_1$,$V_1$,$T_1$). $A$ is taken through a reversible adiabatic process and $B$ through an irreversible ...
  • 111
0 votes
4 answers
90 views

Why does adiabatic expansion occur in the carnot process?

(Spoiler: Why adiabatic expansion happens in Carnot cycle doesn't really answer the question for me.) In the Carno cycle, the open system is first brought into contact with the warm reservoir, which ...
  • 179
0 votes
1 answer
40 views

Calculating the required volume of Helium to put in a weather balloon [closed]

Question I am working on a project where we will launch a weather balloon with some scientific instruments tied beneath the balloon. We fill the balloon with helium from tanks of compressed helium. ...
  • 51
0 votes
1 answer
58 views

How to derive $ TV^{1-\gamma}$? I get $ \frac{T}{V^{1-\gamma}}$ [closed]

For an adiabatic process we have $dQ=0$, thus the first law gives: \begin{align} \mathrm{d}E &= \mathrm{d}W, \\ nC_V \mathrm{d}T &= - P\mathrm{d}V = - \frac{nRT}{V} \mathrm{d}V, \\ \frac{\...
  • 1,126
0 votes
1 answer
27 views

Doubts regarding work and pressure during adiabatic compression of a gas in a cylinder

So, I have doubts regarding the work done on the gas in this situation: Let's say I have an ideal gas inside an adiabatic cylinder fitted with a piston of area $A$. The piston has mass $M$. Outside ...
0 votes
0 answers
40 views

What is symmetry in this context?

I'm reading a paper that was written by a senior undergraduate at my college and I'm having a trouble trying to understand a part of his paper. His paper is on Measuring nonlinear Phase accumulation ...
1 vote
1 answer
44 views

Is vapor pressure conserved during an adiabatic ascent of an air parcel?

Consider an air parcel with relative humidity $H$ and vapor pressure $e$ that experiments an adiabatic lifting process. Obviously the saturating vapor pressure is going to change since said process is ...
  • 642
0 votes
1 answer
60 views

An ideal gas expands into vacuum in an insulated rigid vessel. Which of the followings happens? [closed]

This question came in the Dhaka university admission exam 2018-19. An ideal gas expands into vacuum in an insulated rigid vessel. Which of the following happens? A. no change of internal energy B. a ...
-2 votes
1 answer
28 views

Can a small amount of super-compressed gas cause much cooling upon rapid expansion and contact? [closed]

Generally, a small amount of mass in the range of $0.001$ - $0.01$ kg, even if chilled to tens of degrees below absolute zero in a hypothetical case to test extremes, even with 5000 specific heat and ...
0 votes
1 answer
38 views

Radial dependence of temperature for adiabatic expansion of ideal gas

If the solar wind propagates out adiabatically with a constant speed and can be regarded as an ideal gas, how the solar wind temperature depend on radial distance from the sun $r$, i.e. $T$ as a ...
  • 1
1 vote
1 answer
87 views

Why do internal combustion engines use adiabatic expansion and combustion?

In the gasoline engine, the gasoline mixture is heated at constant volume, followed by adiabatic expansion. In the diesel engine, the mixture is heated at constant pressure, and this is followed by ...
  • 43
1 vote
1 answer
41 views

Finding equation of internal energy in adiabatic process

I am doing a review of thermodynamic and I encounter the following question, Show that if a single-component system is such that $PV^k$ is constant in an adiabatic process (k is a positive constant) ...
0 votes
1 answer
29 views

What is the type of system, if I have an opened container with hot water inside, but no heat input to the system?

I have a school project, where I am trying to generate electricity using TEG modules that are attached to an aluminium container that contains hot water. The container is opened and there is no heat ...
1 vote
0 answers
67 views

Adiabatic expansion of the universe

I was wondering why we consider the universe to expand adiabatically. If the universe is a closed system shouldn't be the energy conserved? Does the adiabatic expansion change the total internal ...
5 votes
2 answers
305 views

Instantaneous eigenstate and time dependent Schrodinger equation

Instantaneous eigenstate $\psi(t)$ is defined as $\hat H(t)\psi(t)=E(t)\psi(t)\tag{1}$ But in the lecture notes of Quantum Physics III MIT (in the section of adiabatic approximation), it is written ...
  • 261
2 votes
1 answer
69 views

Why doesn't temperature decrease with an increase of volume in the syringe?

I made an experiment using a closed syringe with the volume marks. At the beginning, the piston is at $5\rm\, ml$, then I move it to $20\rm\, ml$. Since the change is approximately adiabatic, we can ...
  • 1,128
1 vote
1 answer
76 views

Derivation of astrophysical entropy

The definition of entropy in astrophysics is often actually just the adiabatic constant $K$ relating $P=K\rho^\gamma$ where $\gamma$ is the usual adiabatic index, $P$ is the pressure and $\rho$ is the ...
2 votes
1 answer
80 views

Rabi oscillations within the adiabatic theorem?

I'm studying Rabi oscillations in a two-level system (TLS) with Hamiltonian \begin{align}H(t)=\omega_0 \sigma_z + \Omega \cos(\omega_1 t) \sigma_x.\end{align} The model is usually treated within the ...
1 vote
0 answers
111 views

Question regarding adiabatic process (Ex 12.2 in Blundell's Concepts in Thermal Physics)

It can be derived from first law of thermodynamics that $$dQ=\bigg(\frac{\partial U}{\partial T}\bigg)_V dT +\bigg[\bigg(\frac{\partial U}{\partial V}\bigg)_T+p\bigg]dV$$ On page 119 of the book, a ...
0 votes
2 answers
67 views

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 ...
  • 137
0 votes
1 answer
90 views

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 ...
1 vote
1 answer
44 views

"Classical" adiabatic approximation: please help me understand better

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, ...
  • 921
1 vote
0 answers
41 views

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 ...
  • 9,919
0 votes
1 answer
54 views

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*(...
  • 103
3 votes
1 answer
99 views

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 ...
0 votes
1 answer
57 views

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 ...
  • 1,217
1 vote
1 answer
245 views

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 ...
-1 votes
2 answers
34 views

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 ...
  • 109
1 vote
0 answers
37 views

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
1 answer
64 views

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 ...
3 votes
0 answers
61 views

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 ...
  • 2,577
2 votes
2 answers
107 views

Why is air considered to rise adiabatically?

Do air parcels not push against other air and do work on them? When air molecules within an air parcel bump into air molecules outside the air parcel do they not transfer energy to them?
1 vote
2 answers
65 views

Adiabatic temperature increase given work done on (ideal) gas

I'm playing around with a Euler's method simulation of an adiabatic compression/decompression process on an ideal gas. If I have a volume of gas and I contract its volume slightly, I will be doing ...

1
2 3 4 5
9