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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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 ...
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What is the relation between scattering amplitudes, fluctuations, response functions and correlations in macroscopic equilibrium systems?

In Kardar's book Statistical Physics of Fields, he mentions that that correlations at different length scales can be measured by scattering. If its electric correlations, you would scatter light and ...
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Is the $\mu VE$ ensemble possible to formulate?

I have recently learned about ensembles in statistical mechanics, and I've seen multiple applications and interpretations of the EVN (microcanonical), TVN (canonical), $\mu$VT (grand canonical) and ...
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27 views

How to make two equations dimensionless?

I recently got set this problem and am having trouble scaling the resulting equations. Any help would be appreciated. An incompressible thermal conducting fluid is contained between two infinite ...
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20 views

Fermi Level: chemical potential vs. electrochemical potential

In solid-state physics it is understood that the Fermi-Level is the electrochemical potential. The Fermi-Level is defined to: However, in thermodynamics this formula is referred to as the ...
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Application of surface tension in thermodynamics

I'm writing a paper about surface tension, and have problems with finding literature about application of surface tension in measuring some thermodynamics quantities. Can you help me? Thank you
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1answer
28 views

Entropy reversal in magnets

Entropy is an irreversible phenomenon without any energy supplied to reverse it. I was reading about paramagnetic substances and how dipoles align inside them on application of magnetic field. My ...
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1answer
29 views

How much does a light heat the air around it?

My dad told me to turn off the lights when I'm not using them because it will keep the house cooler. I don't think he is correct that a light can heat up the room. How much of a difference in the ...
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1answer
26 views

Why is Cv used in the adiabatic expansion of Carnot Cycle to calculate internal energy

When I took this class years ago, I simply accepted it as fact. However, now that I'm teaching it, the following bugs me....a lot. Why do they use Cv to describe the change of internal energy during ...
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1answer
28 views

Open systems (Conservation of Energy): is a temperature change possible if a tube is thermally isolated?

Full question: consider an perfectly thermally isolated cylinder. Water is flowing through this cylinder from the entry to the exit. Is it possible for the water flowing through the exit to have a ...
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40 views

Removal of heat from a closed system using electricity

I was thinking this morning about how heat could be removed from a system in such a way that it is stored for future use. My ideas are a form of thermo-electric system that converts heat into ...
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1answer
63 views

Can some one explain about m theory? [on hold]

I am very new to m theory and string theory. I am very through with classical physics and little bits of quantum mechanics. Will you be able to explain why the fact that gravity is a week force being ...
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53 views

If heat can't be transformed into other forms of entropy, why do hot things radiate electromagnetic waves?

The laws of entropy says entropy can only increase. On the other hand, if I take a hot object, it will naturally convert its heat into EM radiation. How is this possible? Does EM radiation count as ...
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38 views

Flow between two infinite plates [on hold]

I recently got set this problem and I was wondering if anyone would be able to give me some hints/intuition on how to solve it. Thanks. An incompressible thermal conducting fluid is contained between ...
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72 views

What is the relationship between entropy and work? [on hold]

Can someone explain the relationship between entropy and work? I've been reading my textbook and looking online but I feel like I'm missing something. Can someone explain it in layman's terms :)
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60 views

Questions on Carnot's theorem

This article on Carnot's theorem states that All heat engines between two heat reservoirs are less efficient than a Carnot heat engine operating between the same reservoirs. However, it only ...
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1answer
18 views

Adiabatic cooling in a closed system

Please forgive me ahead of time if something I say isn't correct, I've just started to read about thermodynamics ever since I developed a fascination for the anti-griddle (by the way does anyone know ...
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36 views

Does work done require interaction between system and surrounding?

There's no work done for a person climbing upstairs because the energy is converted to PE within system only. The person is the system. How true is the above statement?
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35 views

Thermodynamics problem

If water is heated between 273 K and 277 K by providing it heat, a part of heat is used to increase the internal energy of water and rest is done as work. But water's volume decreases between the ...
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p=aV+b, finding Q and L [on hold]

I must find L and Q from p=aV+b. I calculated the L like: ...
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2answers
50 views

Loss of temperature of a sphere [on hold]

I am trying to get an intuition of whether it theoretically seems possible for a living cell (a yeast for example) to regulate its own temperature. Let's consider a spherical living cell which radius ...
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Heat from opposing mirrors

Is it possible to increase the amount of heat drawn from one mirror pointed to the sun by another mirror opposed to it?
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Is there a local canonical ensemble partition function for a Bose-Einstein gas?

The grand canonical partition function for a Bose-Einstein gas is $$ Z_{\text{grand bos}} = \exp \left( \sum_{j=0}^{\infty} -\ln \left( 1-e^{\beta(\mu-\epsilon_j)} \right)g_j \right) $$ where $\beta$ ...
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Calculating stable orbital resonance and other factors into orbits

Firstly here is a brief summary of what I trying to accomplish. From a predetermined total solar system mass , star count in that system, per-star classification and mass I am building a system of ...
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1answer
80 views

How does the hot cup of tea cool down? [duplicate]

I am not sure about my answer. I think that the cup of tea cools down by the following modes: Radiation between the surface of the tea and the air molecules. Conduction between the tea and the cup ...
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1answer
74 views
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Pressure and Temperature in a few-body system

This question is very much related to this other one, and the introduction is the same. If we want to define intensive properties for few-body systems it is not straightforward. I am referring ...
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+50

Non-extensivity in a few body system

Thermodynamics finds application in many areas of physics, many of them sharing the feature of fluid-like or many-body like behavior. However, small systems or few body systems have been studied too ...
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1answer
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Niagara Falls mist

I am at Niagara Falls and noticed that the mist increased significantly at night and in the early morning. I guess it is acting like a cooling tower. Why is this happening?
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Is heat supposed to bounce on an insulator or slowly go through it?

I have a simple flat electric heater at home, fixed on a wall. 50% of the energy is absorbed by the wall !! What would happen if I put some isolation material between the heater and the wall ? Would ...
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42 views

How is pressure an intensive coordinate?

Most textbooks explain intensive coordinates by asking us to consider a system and divide it into two parts. The properties which remain the same will be called intensive and the properties that ...
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27 views

Specific heat capacity at constant volume VS constant pressure

For an ideal gas, why is the specific heat capacity at constant volume lower than the specific heat capacity at constant pressure?
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Traveling Back in Time at the End of the Universe [closed]

I apologize if this question may seem fantastical. Since the heat death of universe is said to be inevitable, is it possible to travel back in time to a younger universe when the time comes? Is that ...
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What are some surprisingly insightful predictions of classical thermodynamics? [closed]

Classical thermodynamics starts from the simplest of postulates. For instance, if you read through the first chapter of Callen's Thermodynamics, you get the impression the author has done little more ...
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can u plz help with these? [closed]

1)LARGE ANGLE OF DEFLECTION OF BETA PARTICLE IS DUE TO: A)HEAD ON COLLISION B)ELECTROSTATIC REPULSION C)ELECTROSTATIC ATTRACTION 2)In outer space there are 10 molecules per cubic cm on an average and ...
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can I maintain the temperature of a metal by electrifying it

Let's say we have a metal that is exposed to high temperatures. This will increase the oscillation of its molecules. Is there a way by applying electrical current to it, to restrict these ...
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The thermal expansion of material

The question is that: they drill a hole in the middle of a metal. Then when this metal is heated, will the hole become larger or smaller? The hole will get bigger, by experiment, but I think that when ...
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Singular isothermal density distribution

Does anyone know where the Singular isothermal density distribution $$ \rho(r)=\frac{\sigma_{V}^{2}}{2\pi\,G\,r^{2}} $$ or how it was derived. Are there any good references on how this equation was ...
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1answer
32 views

phase equilibrium

For a 2 phase closed system : $$d(nG)=(nV)dP-(nS)dT+\Sigma\mu_idn_i$$ now the question is, when we can use formula, $d(nG)=(nV)dP-(nS)dT$, for the above system, instead of the first formula, and why? ...
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96 views

Is heat always associated with Light?

I have found that light always produces heat. The only cases I think heat is absent with light is Fluorescence and Phosphorescence (maybe because they emit low energy but maybe the heat is still ...
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Would a rocky planet orbiting so close to a very hot star eventually vaporize?

I was thinking about the physics behind a hypothetical scenario where a planet the size and the mass of the Earth is orbiting so close to a very hot star and what the long-term fate of such a planet ...
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2answers
69 views

Is it possible to measure temperature using sound?

Is it possible to measure the temperature of something using sound, by blasting sound waves at solid objects, liquids and gasses, then measuring how much sound is reflected or absorbed, to give an ...
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1answer
74 views

Wanted: simple physical representation of the influence of payload onto car tires [duplicate]

From measurements I can tell that weight, as a function of tire pressure increase, is not linear but more something like this: 50kg = 1 change in pressure 100kg = more than 2 changes in pressure, ...
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2answers
62 views

Where do atoms of H and He go when they rise in the atmosphere? [duplicate]

What happens to atoms/molecules of H and He when we let them freely fly in atmosphere do they get into space? Is there any particular way to enumerate the 'force' that drives them upwards? Does ...
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2answers
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Multiplicity vs Partition function

I'm a little confused between all the different notations for the multiplicity and partition function. They're not the same thing, are they? I know that entropy can be expressed as $ S = k \ln\Omega ...
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1answer
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Black plastic balls on reservoir to reduce evaporation - why black?

The story is here It states: The balls sit on top of the water and block the sunlight from hitting it, helping to reduce water evaporation as well as natural contamination and certain ...
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35 views

Is thermal and electrical conductivity correlated for all phases of matter?

After reading this interesting post about why copper is a great heat conductor, I wondered if a plasma would conduct heat better than a gas. Or, are some properties like density more important for ...
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77 views

Do photons have six degrees of freedom?

Calculations involving pressure and volume relationships of photon gas during the cosmologic expansion of the universe posit an adiabatic cooling process with a heat capacity ration of 4/3. This ratio ...
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29 views

The formula for calculating work transfer for a reversible adiabatic compression

Should we not be using Pdv for calculating the work done during a reversible adiabatic process ? Why are we using Vdp ? Can some one please explain this ? (P.S. I'm taking an introductory course on ...
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3answers
63 views

How much effect does painting a domestic radiator have?

Yes, I know it should be called a convector :-) The obvious effect is that a coat of paint, which is generally a thermal insulator, can limit the rate of heat transfer from the metal to the air. But ...
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Isothermal versus Isometric/Isochoric

My impression is that all three have something do with change in internal energy, in thermodynamics. But I cannot tell exactly their relations. First isothermal, which literally means zero ...