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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Which constant is required to calculate the energy in a thermal analysis?

I want to calculate the energy in a thermal analysis. I want to do it in analogy to the electrostatic field, because I'm interested calculating the $H_1$ error in a Finite Element analysis. For ...
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22 views

Is it true that 3 different types of sound produces at different stages while boiling a water? [duplicate]

I have heard this from someone that 3 different types of sound occurs when we boil the water . is it really true ?
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39 views

Thermodynamics phase change question

why is specific volume of Saturated water greater at 1 MPA than at 0.1 MPA during the phase change process check out the T-V diagram here in the link. ...
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49 views

Monte carlo simulation for continuous spin model (e.g. XY or Heisenberg model)

Unlike the Ising model, the XY model and the Heisenberg model have a continuous spectrum. So one need discretize them for a numerical simulation. But how to make sure the discretization procedure ...
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38 views

Why do metal surfaces reflect thermal signature?

I recently borrowed a thermal camera from a friend and I tried to observe my palm print over a reflective metallic plate. When I looked at it through the camera, it reflected my thermal signature too. ...
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22 views

Third principle of Nernst [duplicate]

I wonder how can I prove the fulfillment of the third principle of Nernst of a body that obeys the next expression.
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1answer
70 views

Quadratic versus other types of degrees of freedom

In my text book I have the following question and after thinking about this one for hours, I can't figure out what they're getting at: In Section 2.5* I quoted a theorem on the multiplicity of any ...
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44 views

How much energy would the Human Torch need? [duplicate]

I wasn't sure whether to put this in the SciFi section or here, but since I'm interested in a physical quantity,so I decided to ask it here. I was wondering about approximately how much energy would ...
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31 views

Simple Conduction Simulation

What is the simplest way to simulate heat conduction on a 2D plane? What I want to do is have 1024x1024 2D plane of uniform temperature 0°C and specify the temperature of a cartesian coordinate. ...
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65 views

Calculating height and evaluating the vicinity of a peak in a multiplicity function for a two-state paramagnet

I have to calculate the height and width of the multiplicity function for a two-state paramagnet. I'm supposed to do this analogously to the method in the text book, which I will try to outline below. ...
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32 views

Is It Possible To Have Temperature Below Absolute Scale? [duplicate]

Guys I have a doubt Is it possible to maintain the temperature of any Substance Below the Absolute Scale?
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48 views

Steam Turbine Inlet Velocity

Consider an ideal steam turbine. The power generated by a steam turbine comes down to the torque and the angular velocity, which is ultimately dependent on the velocity at which the flow enters the ...
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47 views

Which function denotes the energy of thermal motion within a system?

In thermodynamics, the heat $Q$ is defined as a type of energy in transfer, and is not a state function, which function denotes the energy of thermal motion within a system? 1) $TS$, (there is a ...
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32 views

At what gap width between two plates does convection not occur?

Does the Grashof number lead to the answer? The Wikipedia article (https://en.wikipedia.org/wiki/Grashof_number) yields an equation for vertical plates $$Gr_L = \frac{g\beta(T_s-T_\infty ...
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68 views

Derivation of Van der Waal's Equation from Helmholtz Free Energy

From the following equation $$ f(T,v) = f_{id}(T,v) - RT \ln\bigg(1-\frac{b}{v}\bigg)-\frac{a}{v}$$ how do I derive Van der Waal's equation. In the equation above, $f$ and $f_{id}$ are the Helmholtz ...
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56 views

Heat engine efficiency, compression ratio vs temperatures

I want to understand the role or even existence of a cold reservoir in the Otto cycle gasoline engine. The efficiency of the Otto engine is given as a function of compression ratio $$ ...
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1answer
98 views

Boltzmann Distribution of Electrons in Confining Potential

I have a particle simulation wherein many non-interacting electrons are trapped in a electric potential well. I would expect, and therefore I initialize according to this, that the electrons would ...
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30 views

SInce heat is a vibration in solids, isn't it just small scale sound? [duplicate]

On an atomic scale I think of electrons hitting positive ions in an electric lattice. Most energy there is heat energy. If I think of ball bearings flying through a large lattice, I think sound is ...
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58 views

Canonical ensemble, energy, heat bath

I am studying through the book Thermodynamics and Statistical Mechanics by Walter Greiner and I’ve got a couple of doubts when I was reading about the classical ensembles, specially the Canonical ...
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55 views

On Thermodynamics of Spontaneity of the Reduction-Oxidation Chemical Reactions

According to the first and second law for a closed system containing different chemicals we have \begin{align} &\delta Q - \delta W = dU = T dS - p dV +\sum_i \mu_i d N_i\\ ...
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33 views

Modeling an Adiabatic Expansion (EES)

How would one model an isentropic (reversible) adiabatic expansion using thermodynamic software in order to determine isentropic work? What I am looking for is an actual pressure-volume curve for the ...
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1answer
49 views

About state function [duplicate]

As I undersand in thermodynamics, a gas with an equation of state $f(V,T,p)=0$ will need only 2 variables (e.g $V$ and $p$) to determine its state. Regarding this question: I still don't ...
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55 views

Difference between Residual Function and Excess Property

Sengers describes the deviation function as the difference of the actual mixture property and as determined from a model. If this model happens to be the ideal gas model, then it is also called ...
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19 views

Distribution of temperature in a plume of a jet

The exaust gases of a plume of a missile have a distribution in temperature and in density vs. distance from the nozzle. Using a CFD software it is quite simple to get such distribution. Is there some ...
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79 views

Units kT = 1… why?

Why is it convenient to choose units kT=1? It came up in this paper: http://jfi.uchicago.edu/~leop/SciencePapers/scaling%20and%20universality%20in%20statistical%20physics.pdf in page 4, equation ...
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67 views

is boiling of water an isobaric process?

Is the conversion of water into steam at 100°C an isobaric process? It is an isothermal process, but does pressure rain constant during this process?Please explain as well..
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18 views

I need to calculate the temperature of some flat copper wire as it loses contact with a chilled capstan roller

I need some help in designing a system for cooling wire as it comes off a resistance annealer. I need to calculate the temperature of that flat copper wire as it comes off a chilled roller (call it a ...
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1answer
80 views

How to prove R value for insulation?

I ran some tests on different types of insulation. I heated water, and placed it into an insulated box. The temperature was recorded every minute, for the water, as well as the air. The insulation ...
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36 views

Thermal Conduction through sphere

In general, a sphere with conductivity $\kappa$, heat capacity per unit volume $C$ and radius $R$ obeys the differential equation at time t: $$C\frac{\partial T}{\partial t} = \kappa \frac{\partial^2 ...
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41 views

How to calculate net power output of heated, expanding air?

I'm interested in designing and building a Stirling engine which uses air that has been heated, which expands and then acts upon a piston producing power. There is a fixed amount of air inside the ...
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1answer
60 views

Enthalpic Excess - Regular Solution Upon Mixing

My professor, in his handout, says the following about this diagram : For $\beta>+2$ there are two minima and phase separation occurs driven by unfavourable enthalpic interactions. I ...
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32 views

Hamiltonian (temperature?) and frame of reference

So we can define a particle by defining its kinetic and potential energy, knowing that we can get a wavefunction describing a particle. But the kinetic energy involves motion, and motion can be ...
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24 views

If maximal work is extracted, in what manner does the heat flow between bodies?

There are two bodies starting with different temperatures and specific heat capacities (for simplicity assume that the bodies are solid to the volumes are constant). Let the rate of heat flow from ...
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1answer
54 views

Exception to weight of hot vs cold water?

I have seen the various posts regarding the comparison of weight of heated and cold water.But is there any contradiction?I live in really hot conditions and as such tap water literally 'boils' ...
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38 views

Which metal will be on the surface after solidification?

I know that there are some metals that just "like" to be on a surface, so if I make an alloy of such metal and some other metal, the first one will be on the surface after solidification of initially ...
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17 views

Water Displacement in the Oceans As a result of Global Warming [duplicate]

Not sure if this is the right place to ask this but here goes. If the north pole ice sheets melt, everyone agrees this would be a bad thing, however one of the reasons they state for this being a bad ...
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40 views

How to calculate the amount of energy in joules/s that gas oven uses?

I know there may be missing information, but my question is really simple and yet I haven't found an answer to it. To make things easy, let's assume we have a $40×40×40$ cm oven that we want to keep ...
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2answers
54 views

Would adding water after heating decrease the overall heat, when compared to adding the water before heating for the same period of time?

I was rather cold last night, and warmed up a cup of water to drink in the microwave. I put it in for 60 seconds, but it came out boiling hot, so I put a bit of cold water in with the hot water, and ...
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45 views

How come evaporation is possible? [duplicate]

If I have wet clothes and put them on the ground and let the Sun shine on them, they dry as water evaporates. But water should evaporate at 100 degrees Celsius so how come they go dry if it's just ...
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16 views

Understanding how clouds form: warm air near the earth's surface?

I'm trying to understand how clouds are formed. I've read that it begins with air near the earth's surface heating up. But I'm hearing two different reasons for how this happens: Air pressure near ...
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1answer
49 views

What is the relation between isothermal process and its surrounding?

In an isothermal process the temperature of a system remains constant but may or may not be similar to temperature of surroundings How is this possible?
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1answer
70 views

Suggest why electrical power input P1 differs from power used P2

We have done an experiment heating water with a wire element and have determined it takes 21.5964 watts to heat 200ml of water to a specific temperature in 10 minutes. However the power of the ...
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12 views

Does transverse flow always assist in mixed convection?

I am dealing with both natural convection and transverse forced convection over a flat plate. There are 4 different situations: Upward-facing cold plate Downward facing cold plate Upward facing hot ...
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1answer
78 views

Using Jacobians to prove an identity

I have to prove the identity $$ \left(\frac{\partial U}{\partial V}\right)_T=T\left(\frac{\partial p}{\partial T}\right)_V-p $$ I know how to do this using Maxwell's relations, but the assignment ...
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46 views

Landau free energy

I am reading the statistical mechanics by Pathria in Chap 12. I have a question about the Landau free energy. What is the physical reasoning for that the free energy could be a functional of the order ...
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62 views

Cooling power for cloud chamber

I'd like to build a small Peltier cell cooled cloud chamber. The cold surface would be a copper sheet with a surface of 200x200 millimeters. Is there a way to even guess the cooling power needed to ...
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17 views

Is there a way to tell the rate of temperature change due to provided energy?

Let's say we have an isolated system containing two bodies with different temperatures. The bodies are touching each other. Is there a way to tell how long will it take them to reach thermodynamic ...
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46 views

Proving $RTln(a_i)$ equal to non PV work done by system,where $a_i$ is activity

First of all many here will might say that it is Chemistry question.If you think so then read this article and then answer question. Question is --- We know chemical potential is defined as $\mu_i ...
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1answer
74 views

Heat flow in a hollow cylinder

Consider a hollow cylinder of different outer radius and inner radius and two different temperatures are maintained at the outer and inner surfaces such that inner temperature is higher. Because of ...
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1answer
160 views

If fans increase the heat of the air and this DIY AC decreases it, why don't they neutralize eachother?

Please try to answer in layman terms, i am only starting to study thermodynamics (And physics) In my book one of the curiosity parts gives that fans don't actually cool the room but by hitting the ...