Covers the study of (mostly homogeneous) macroscopic systems from a heat/energy/entropy point of view. Maybe combine with [tag:statistical-mechanics].

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Quanta exchange between 2 harmonic oscillators during an Otto cycle

The focus of my current studies lies on the "Quantum Otto cycle" (e.g. presented on the first pages of this paper). The "machine" as well as the "baths" are represented by harmonic oscillators. Both ...
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30 views

Could Something Infinitely Heat Up?

If there was a perfect environment, and something was able to continue to heat up indefinitely, what would happen?.. What would be the outcome of something continuously heating up?
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60 views

Are there any liquid that becomes solid on heating under room temperature?

The title says it all. When I searched around, there are answers which involve extra steps like super cooling and then heating or exposing the liquid to high pressure. But I would like to know if ...
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26 views

Linear thermal expansion from statistical mechanics?

I came across a question recently regarding work done by an expanding metal and the origin of the energy used for the work, and most of the responses pointed the person to look more at the enthalpy ...
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26 views

Microscopic Definition of Heat and Work

If I am given a statistical System, then I can define state-variables like Energy, Entropy or other Observables, and then I can (at least for equilibrium states) give the Change of Energy as: \begin{...
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13 views

How the degrees of freedom for gas molecules affect energy

It seems a bit unclear to me how degrees of freedom help judge the amount of kinetics energy in the system. from the formula for the energy of molecule ε = u0 + (v/2)kT it can be inferred that the ...
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24 views

Calculating heat distribution along 1D line segment?

I want to calculate temperature distribution where the heating power of $P_0$ is uniformly distributed over 1D bar TO calculate, there is heat equation. $$ \frac{\partial T}{\partial t}=\frac{\...
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28 views

Energy inside a box of air with temperature variation

How to find the energy of a column of air enclosed in a box (assume adiabatic) with a temperature variation $T(z)$ in the vertical ($z$ direction) in a uniform gravitation field? I think the total ...
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24 views

Relations between Maxwell-Boltzmann's distribution and the n-body problem velocities distribution

Solving the n-body problem numerically and finding the velocities distribution, one finds that it's quite similar to Maxwell-Boltzmann's velocity distribution. This is quite suprising because of the ...
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38 views

Energy dissipation in spinning wheel

I was given the following question in a test. A spinning wheel A is brought in contact with an identical wheel spinning at identical speed.The wheels slow down under the action of friction.Which ...
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17 views

Temperature of throttled flow

In a pipe with a throat, closed off to the left, I'm pouring in $\dot{n}$ atoms per second from the left. These atoms combine and do a chemical reaction, which releases energy. To the right, past the ...
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40 views

why water can exist in both liquid and vapour state at critical point?

Water can exist in both liquid and vapour state simultaneously at 22,055 MPa and 373°c. why in these conditions water exist in both states. How can we know whether water is in liquid state or in ...
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46 views

Justification of the State Postulate

I have just started thermodynamics (not with statistical approach but with macroscopic approach), in which the state postulate reads Only two independent intensive properties of a simple ...
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32 views

Finned Surface (Corrected Length)

I have to analyze a rectangular convective tip and determine a few factors. Then I have to use the corrected length (Lc) approach and calculate the same factors. My issue is with the formula for $A_{...
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35 views

Meaning of $\frac{1}{\beta} \frac{\partial \ln{Z}}{\partial X}$ in arbitrary ensembles with X being a sharp Observable of the System

I often find the statement, that for an arbitrary ensemble with Observables $O_i$ of which only the mean value is known, and $\tilde{O}_j$ that are known exactly, the partition function $Z_{\vec{\...
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26 views

Isothermal expansion of a cavity containing electromagnetic waves?

The cavity is perfectly reflecting , and simulates a black body . Is it that during an isothermal expansion of a cavity containing electromagnetic waves the internal energy density is constant and ...
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8 views

what are the things that affect the ion mobility of a particular material?

what factors are important in ionic transition in a substance? please use easy word to answer as I am a high school student.
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20 views

Computing the energy of a heat source

My son and a friend are doing a science fair project on thermoelectricity. While they understand ZT, the figure of merit conceptually, they do not know how to calculate efficiency. It's easy for ...
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45 views

Validity of Gibbs-Dalton Law

I know that the Gibbs-Dalton law valid for an ideal gas mixture of ideal gas components. Does it also hold in the case of ideal gas mixture of real gas components? For example, could I say the ...
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28 views

Ice and water mixed and entropy

In any introductory book, everybody has atleast done these type of questions where water at a high temp is mixed with ice and final temp and mass is asked with the understanding that zeroth law define ...
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25 views

What could be the anharmonicity effect if phonon interact with a tilted interface?

If Phonon propagates through c-axis grown structure and at the end reach a tilted interface of GaN, what phenomena will appear there? How anharmonicity is going to effect the phonon propagation there?...
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32 views

Why changes in the degrees of freedom implies changes in the internal energy?

In Thermodynamics we describe equilibrium states of macroscopic systems. For those equilibrium states we make a description giving one macroscopic coordinate for each measured degree of freedom (like ...
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16 views

Increase in temperature of metal piece during filing explain by the Gibb's equation?

When we file the metal the surface of the metal gets worn out in the form of small pieces of metal. The file acts as medium to transpher the energy from the body to the metal piece in the form of work....
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34 views

What happens when a semipermeable membrane allows only one solute to pass through?

I'm essentially a medical student where we deal a lot with osmosis. But when we are taught, it is done generally with only a single solute in consideration. What if two different solutes are used on ...
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27 views

easier ways to cool things using electricity compared to phase changer

I can't seem to find any other ways to cool things using electricity. I understand how a phase changer works, but the whole things takes up alot of energy to cool down quite a few degrees and is ...
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46 views

applications of second law of thermodynamics

Second law of thermodynamics applies ONLY to thermal engines? Only in cases where we have heat involved? It won't apply to a mechanical machine that works without friction, right? Also will it apply ...
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19 views

Can the flow of hydrogen in a fuel cell be modelled as adiabatic?

Okay, so right off the bat I'll admit I need this for a problem I'm working on. Not homework though, a project, as a matter of fact. I'm considering taking compressibility effects into account, but I'...
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30 views

Computing Maximum Heat Capacity

I've encountered a problem in my statistical mechanics class that I'm not sure I'm approaching correctly: Consider a system of N interacting spins. At low temperatures, the interactions ensure that ...
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16 views

what are the direct real life applications of analysis of ferromagnetic materials?

I carried out Statistical analysis of ferromagnetic materials using Monte Carlo simulation, what are the contribution to knowledge based on the research work
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36 views

Relation between Light Intensity and temperature of air

First, I switched on my bulb but not the air-conditioner. Next I switched on my air-conditioner and yet kept the bulb on. I noticed that when the air-conditioner was switched on , the same bulb's ...
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19 views

How much power is being actually delivered by an electric heater to a cooking pan?

I've been doing experiments on an electric heater heating a cooking pan filled with 2 litres of water, from 20°C to 70°C; now I'm trying to draw a theoretical heat transfer model thath should match ...
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88 views

Why formation energy calculation is essential in DFT studies?

I use Density Functional Theory (DFT) to calculate the electronic properties of doped molecules/materials. By doping, I mean both substitutional doping and interstitial doping. At present, I optimize ...
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23 views

Lets consider a cube with side $2$, which is cooling in an environment. Find its temperature at any point at any time: $u(x,y,z,t)$

Lets consider a cube with side $2$, which has an initial temperature of $1$°K and it is cooling in an environment of temperature $0$°K. Find its temperature at any point at any time: $u(x,y,z,t)$. ...
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14 views

How can I calculate the rate of mass air flow being supplied by the AHU in a room?

I need to calculate the mass air flow being supplied by the AHU so I can find the total heat being supplied to the room. However, I only have the following sensor measurement - Supply Temperature, ...
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28 views

Is emissivity always equal to absorbtivity in case of any arbitrary body?

We get from the Kirchoff's Law that at thermal equilibrium, e=a can be easily proved. But is this result always valid?
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23 views

How to have a power plant that works with a 3stage turbine but with just one stage of reheating

There is a power plant that has a 3-stage turbine (hi-press,medium-press,low-press) but with just one reheat stage. The cycle is thermal,so the working fluid gets QH from boiler,goes to turbine and ...
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39 views

What is the use of thermal boundary layer and velocity boundary layer?

In heat transfer by convection, why must we show the thermal boundary layer and the velocity boundary layer. What do they signify? Also how are these terms related to the Prandtl number? And what is ...
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23 views

Separating Interaction of Heat from Electricity?

I have a rod where electricity of frequencies 1-360 Hz is passed through. It is affected by heat. I am evaluating the energy involved in such a process, contributed by electricity and heat. The ...
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44 views

Gravitational waves parallel

Just an idea to illustrate the gravitational waves. This kind of analogy is proposed: When you have a rotational motion of the fluid, some small amount of the energy is radiated as a pressure ...
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13 views

How to express Darcy velocity as a function of mobility and capillary pressure?

I have a problem with deriving a certain expression for the Darcy velocity of water, when we have a piston like displacement of oil with water. The expression I am supposed to show is the following: $...
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41 views

car dashboard problem

I stumbled upon this question while I was driving my car. On my dashboard I have fuel gauge and engine temperature gauge next to each other, look at the pic: http://i.stack.imgur.com/aDgKj.png Fuel ...
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17 views

What's the simplest, first order way to calculate the temperature change in this scenario?

I am trying to model this experiment in a simple (i.e., relatively analytic, non-computational) way. I have a little square of a thin film (10s of nanometers thin) of material A, on a relatively ...
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27 views

Hagedorn temperature as a control parameter of saddle - node bifurcation

Can we interpret the Hagedorn temperature as a control bifurcation of equilibrium parameter of the saddle - node type?
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20 views

What is temperature dependence (Schottky defects)?

The problem requires us to use the following property to determine the temperature dependence: For a system in thermal equilibrium in a heat bath at temperature $T$ the Helmholtz free energy is a ...
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37 views

Obtain an exact expression for the heat capacity of the system

Before anyone mentions it, yes I did my research and found this question on this site. My question is his exact question, but I'd like some clarification or maybe a bit more explanation than the one ...
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24 views

Understanding the concept of temperature vs. mean energy/heat capacity of a system

I need help understanding a concept in thermodynamics. What is the relationship between temperature and mean energy? What is the relationship between temperature and heat capacity? What I know: $...
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19 views

Can I find equation of state if I have a type of potential?

How can I find equation of state if I have a type of potential? For example, if I want to take into account ion-ion, ion-electron, electron-electron interaction in white dwarfs.
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63 views

Thermodynamics questions

does a refrigerator full of food consume more power if the room temperature is 20 degree Celsius than when it is 15 degree Celsius? or is the power consumption the same?
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Name of the fourth entropy potential

Wikipedia's "Free Entropy" page lists three entropy potentials: Entropy, $S$, with natural variables $U$ and $V$ Massieu Potential / Helmholtz Free Entropy, $\Phi$, with natural variables $1/T$ and $...
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52 views

Please help me with this doubt from thermodynamics

My textbook says that net rate of heat transfer due to radiation is $\epsilon \sigma A(T^4-T_o^4)$ but i couldn't understand it. Rate of emission is $\epsilon \sigma A T^4$ and rate of absorption is $...