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

learn more… | top users | synonyms

2
votes
1answer
62 views

Specific heat capacity for Adiabatic process

We can define infinite number of specific heat capacities between two temperatures(e.g $c_p ,c_v$) . Could we do that for an adiabatic process. As for adiabatic process heat addition or removal is ...
-1
votes
0answers
31 views

Interpreting conical intersection in quantum adiabatic evolution

Recently, I have studied a particular quantum adiabatic algorithm. When I plot the eigenvalues of the ground and first excited state against normalized time $s$, there appears a conical intersection. ...
2
votes
1answer
112 views

Simplest Live Demonstration of Adiabatic Transport

I have to give a presentation on Berry phase. I would like to give the simplest live demonstration of adiabatic transport. If I move an object in a loop and return that object back into its original ...
1
vote
0answers
223 views

Intuition behind transforming a Hamiltonian expressed in momentum representation in eigenbasis [on hold]

This question is a supplement to a previous question on the same paper. In the section 4.1 of Quantum Computation by Adiabatic Evolution, Farhi et al proposes a quantum adiabatic algorithm to solve ...
0
votes
2answers
217 views

Work done in adiabatic reversible process

I was solving a problem on turbine.the steam works on turbine adiabatic reversibly .Is change in enthalpy or is it change in internal energy which equal this work?
6
votes
2answers
369 views

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)....
4
votes
2answers
4k views

Comparison between isobaric, isothermal and adiabatic expansion

Please check if my understandings of these terms are right because they are a bit confusing to me. For all three types of expansions, a change in volume means work is done by the system to the ...
4
votes
1answer
86 views

Ground state of an adiabatic Hamiltonian as an eigenstate of the total spin

I am going through Quantum Adiabatic Evolution Algorithms with Different Paths by Farhi et al. Here, the authors propose to add a special term to the adiabatic Hamiltonian so that the path of the ...
2
votes
3answers
65 views

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 ...
0
votes
0answers
89 views

Why does the method below work?

Please explain why this method works. I get this idea when try to solve adiabatic gas expansion by using numerical method. The analytic/exact solution for the expansion will be $PV^\gamma$=constant. ...
-1
votes
0answers
48 views

Improved gap estimates for quantum adiabatic evolution

In his PhD thesis, Daniel Nagaj mentioned that Deift† et al has tightened the relationship between the adiabatic evolution time $T$ and the energy gap between the ground state and first excited state, ...
7
votes
1answer
398 views

Adiabatic approximation

The adiabatic approximation for solid state systems is rather radical. I was wondering in which cases it breaks down. As it is based on the idea of the nuclii being much heavier than the electrons I ...
1
vote
0answers
17 views

Slowly Varying Functions for Adiabatic Invariants - The Same as Karamata's?

In section 49 (and 50) of Landau and Lifschitz's "Classical Mechanics", adiabatic invariants are discussed, which are related to functions which vary adiabatically or "slowly" with time. Admittedly ...
0
votes
1answer
31 views

Two rising bubbles of differing temperatures

Consider two bubbles rising through some medium (water, for example). Given that the two bubbles have the same initial size, pressure, and temperature but differing velocities, which bubble will be ...
4
votes
2answers
193 views

Condition for adiabatic approximation, derivation?

In quantum mechanics it is said that an adiabatic approximation is valid when $$T\gg \frac{\hbar}{\Delta E},$$ where $T$ is the time scale of variation of the Hamiltonian and $\Delta E$ is the typical ...
0
votes
0answers
21 views

Are there any specific examples of the application of Lewis-Riesenfeld procedure to time dependent Hamiltonians in QM?

Lewis-Riesenfeld invariant theory is a theory applicable to solve time-dependent Schrodinger equations. I have always encountered the theory related to the procedure, however never encountered any ...
2
votes
1answer
200 views

Bernoulli Equation for isentropic ideal gas flow

If one derives the Bernoulli Equation for the isentropic ideal gas flow you get: $$ \frac{1}{2}v^2 + g z + \left(\frac{\kappa}{\kappa -1} \right) \frac{p}{\rho} = const. $$ Two questions: Is ...
0
votes
2answers
61 views

Free Expansion Of and Ideal Gas

We know that in free expansion of an ideal gas, no heat enters or leaves the system. We also know that $P_\text{initial}V_\text{initial}=P_\text{final}V_\text{final}$ is valid. If heat exchange ...
3
votes
2answers
312 views

Adiabatically stretching a rubber band

When a rubber band is stretched it heats up, but how can this be explained (from the microscopic view) in the case of an adiabatic expansion (meaning that the entropy remains constant). Further more ...
1
vote
2answers
40 views

Adiabatic expansion on $(P,T)$ diagram

Consider a certain substance which is described by pressure $P$, volume $V$ and temperature $T$. In one thermodynamics exercise I was asked to draw one adiabatic expansion from $V_1$ to $V_2$ in a $(P,...
2
votes
1answer
59 views

Entropy generation during irreversible adiabatic expansion

During irreversible adiabatic expansion entropy is generated. It means that the gas expands to as greater volume than that during reversible adiabatic expansion for the same change in pressure. How ...
0
votes
0answers
21 views

What makes the thermal insulation materials differ from normal ones?

Is free electrons are playing a critical part? If the answer is yes, then what would happen if I use a positively charged metal without free electrons to transmit heat?
6
votes
2answers
192 views

Why are sound waves adiabatic?

I want to know why we can treat sound waves as an adiabatic process. Precisely, I know that pressure and density vibrations occur so fast that molecules have no time to exchange energy (I might be ...
1
vote
2answers
100 views

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 ...
0
votes
1answer
80 views

Difference between throtling and adiabatic expansion

Throttling process is an isoenthalpic process.$$U+PV=constant.$$ during throttling process does the gas do work at the cost of internal energy such that its temperature decreases? Then what is the ...
1
vote
1answer
62 views

Relation between Pressure and volume in adiabatic process?

Why in adiabatic compression and expansion small volumetric change occurs while in isothermic compression or expansion very small pressure is applied and volume changes very significantly i am ...
1
vote
1answer
55 views

Adiabatic compression and expansion and isothermal expansion? [closed]

Please help me in understanding the concepts Why in adiabatic compression and expansion small volumetric change occurs while in isothermic compression or expansion very small pressure is applied ...
1
vote
1answer
36 views

Plotting isothermals and adiabats

first time poster in this site. I am trying to create a small program to make a graph of the Carnot cycle. For isothermals I am simply trying to look for points where P*V would give the same ...
1
vote
1answer
37 views

Calculating heat absorbed from expanding gas [closed]

I'm trying to calculate the amount of heat absorbed per kg of different types of gas, namely compressed air and carbon dioxide. Starting with carbon dioxide, I found that the Joule-Thompson ...
0
votes
1answer
68 views

reversible vs irreversible work for adiabatic process

I have a gas transitioning adiabatically between A ($P_1$, $V_1$) and B ($P_2$, $V_2$) where $P_1>P_2$ and $V_2>V_1$. The question is to determine the net work done on the gas if the gas is ...
0
votes
1answer
551 views

Is there a single Poisson constant for mixtures of gases?

Let's say air consists of 79% nitrogen and 21% diatomic gas. To perform calculations on $\Delta H$ on adiabatic expansions, instead of taking them as individual parts, can I take the air to be a ...
1
vote
0answers
190 views

Calculating mass flow rate, force of thrust produced compressed air discharge

This one's a bit of a doozy, so please feel free to comment on any one single part or parts to this physics problem. The setup is simple--I have a container (an empty bottle) which I fill with a ...
0
votes
1answer
55 views

Filling of a gas in a cylinder

The problem statement is as follows: An insulated rigid vessel of volume $V$ initially contains $N_i$ moles of an ideal gas at temperature $T_i$. A pipe is now connected to the vessel and the same ...
0
votes
1answer
62 views

Adiabatic expansion of ideal gas and dependence of temperature on volume

We know that for an ideal gas $$PV=nRT,$$ where $P$ is pressure, $V$ volume, $n$ amount of substance in moles, and $T$ the temperature of the gas. We can easily derive that, for a (non-free) ...
0
votes
1answer
71 views

How to calculate the entropy change in an adiabatic process? [closed]

A 2 cm long, 10 mm diameter and 1.5 kW electric heater is used to heat 30 kg water in an insulated container.The initial and final temperatures of the water are 25 C and 90 C respectively. Calculate ...
0
votes
2answers
942 views

What is polytropic index?

What is polytropic index? What is the connection between it and work of an adiabatic system? I tried surfing but didn't able to find a proper answer for that.
1
vote
3answers
102 views

How can a reversible adiabatic expansion not increase entropy?

In the second stage of the Carnot cycle, a gas is thermally insulated and allowed to expand and do work on the piston. I understand the reason people give is that because entropy is $\,dS = \,dQ/T$ ...
6
votes
1answer
107 views

Adiabatic expansion in the atmosphere

When an air parcel rises and cools adiabatically, it is said that there is no heat transfer as work is done on the surrounding atmosphere as the parcel expands. The parcel loses internal energy and ...
1
vote
1answer
95 views

Is there a proof that adiabatic processes only occur in thermally isolated systems?

This question arose when I read somewhere that adiabatic processes can only be done in thermally isolated systems and isothermal processes can only be done in thermally non-isolated system. Now, let'...
3
votes
1answer
298 views

Intuition behind Hamiltonian

I am reading this paper by Das et al. which converts Deutsch's algorithm into an adiabatic quantum algorithm. I don't get the intuition behind the initial and final Hamiltonians. If defines the ...
3
votes
1answer
86 views

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 ...
4
votes
1answer
2k views

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 ...
1
vote
0answers
65 views

Why doesn't entropy get decreased in adiabatic expansion process?

I was reading the second step of Carnot cycle in which the system undergoes adiabatic expansion doing work & thus decreasing the internal energy of itself. The entropy didn't change as no further ...
4
votes
0answers
218 views

Adiabatic invariant and Liouville's theorem

It appears that many people have tried to show adiabatic theorem from Liouville's theorem, e.g., Li's note, or at least tried to find some relations, e.g., Rugh, Adib and Tong's lecture notes Sec. 4.6....
0
votes
1answer
68 views

Reversible adiabatic process

I was studying some basic thermodynamics concepts and I noticed that in reversible processes in my book always the adiabatic word is used. So are all reversible processes adiabatic? (ques 1) Or ...
0
votes
3answers
12k views

Work Done by an Adiabatic Expansion

I am given the information that a parcel of air expands adiabatically (no exchange of heat between parcel and its surroundings) to five times its original volume, and its initial temperature is 20° C. ...
2
votes
0answers
58 views

Ordering of eigenstates in the quantum adiabatic theorem

Suppose we have an 'initial' Hamiltonian $H_{i}$ whose eigenvalues are all non-degenerate, which we order as follows: $ E^{0}_{i} < E^{1}_{i} < \dots < E^{N-2}_{i} < E^{N-1}_{i}$ Suppose ...
2
votes
1answer
85 views

Sources to learn about Berry phases and Adiabatic Theorem

I recently went through Griffiths' Quantum Mechanics text and there is a chapter called the Adiabatic Theorem that includes Berry phase and the Aharonov-Bohm effect. As I found them very ...
0
votes
1answer
43 views

Why the air is more compressed near to the ground

I'm studying the adiabatic effect of the air on the atmosphere but i can't understand why the compression near to the ground is higher, is something relate to the higher pressure caused by the earth ...
1
vote
0answers
37 views

Adiabatic Surfaces in thermodynamics

In some lecture notes on thermodynamics there is a discussion as to whether by assuming the first law of thermodynamics alone we can prove the existence of a adiabatic surface in three dimensions. To ...