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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14 views

Equipartition Theory at room temperature.

I read a statement about participation theory. The equipartition theorem is generally valid only at high temper- ature, so that the thermal energy is larger than the energy gap between ...
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0answers
11 views

chemical thermodynamic [on hold]

Calculate U and H for each of the following changes in state of 2.50 mol of a perfect monatomic gas with CV,m 1.5R for all temperatures: (a) (1.50 atm, 400 K) → (3.00 atm, 600 K); (b) (2.50 atm, 20.0 ...
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2answers
31 views

Temperature rise during friction

Why the temperature increase when the load increase during friction ? Why the temperature increase when the contract time increase during friction?
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1answer
13 views

What the effect of thermal diffusivity on temperature rise during friction

If we have two material in friction wich metal will produce the temperature?the metal with lower diffusivity or with higher diffusivity will be the source of temperature
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1answer
48 views

Dr. Pierre-Marie Robitaille: On the Validity of Kirchhoff's Law

Lately I've been researching about the black-body spectrum and the historical development of Planck's Law. I mainly wanted to understand a little bit more why many different objects (Stars, Hot ...
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1answer
41 views

Temperature increase during friction

There is pin made of Asbestos and two disc material Aluminum and steel in first experiment i used Aluminum disc with asbestos pin in wear test the disc is rotating and the asbestos was in frictional ...
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1answer
27 views

Emulating changes in building temperature

I need to emulate what happens to the temperature in a building when turning the heating on and off, for a kind of computer simulation. I don't even know where to start, so I hope you can help me out. ...
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1answer
29 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 ...
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0answers
9 views

Range of thermocouples

Why do thermocouples have a restricted range of temperature that can measure, say for example some go from –200 °C to +268 °C, what makes them to be useless below or above?, I know above may become ...
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1answer
55 views

Is the MaxEnt “interpretation” of statistical mechanics the current mainstream approach?

I've only recently started studying statistical mechanics and I'm quite confused with the MaxEnt and anti-MaxEnt ideas. I'm looking for a concise answer, if it is possible, not really a description ...
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1answer
26 views

How to reduce cooling time of hot aluminum casting / block?

I am doing project on "reduction of cooling time of hot Aluminium casting/block". Aluminum casting / block temperature is 250degree C (532 K), size diameter 600mm x 150mm and weight 25kg. In order ...
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0answers
24 views

entropy balance equation in thermodynamics [on hold]

can any body help me to prove the following entropy balance equation. \begin{equation} T \frac{ds}{dt}=- div \mathbf{q} \end{equation} where $T$ is absolute temperature and $s$ is entropy $\mathbf{q}$ ...
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1answer
25 views

Thermal expansion of metal spring

I am attempting to figure out why a laser layout tool I have is drifting over time. It was designed with a small adjustment mechanism that relies on a spring to apply pressure to a fulcrum that ...
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0answers
30 views

change in free energy at natural state

I am styding a book on thermoelasticity, here free energy $f(e_{ij},T)$ is expended into taylor series in the vicinity of the natural state (when $e_{ij}=0$,$T=T_0$) and entropy s such that ...
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0answers
25 views

What is the pressure of a charged gas?

I have $N$ ${\rm H}^+$ gas molecules in a sealed, electrically insulated container. What equation can I use to accurately calculate the pressure of the gas? It seems to me that $PV = nRT$ will not ...
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1answer
59 views

What ice pack formula can hold the largest energy difference?

I recently bought some Freez Pak brand ice packs. The label advertises: "Colder Than Ice". I realize now that it's just a stupid marketing claim, but at first, it got me wondering if they had some ...
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0answers
20 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 ...
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0answers
13 views

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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1answer
43 views

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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0answers
46 views

How to make two equations dimensionless? [on hold]

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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1answer
43 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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0answers
16 views

Application of surface tension in thermodynamics [on hold]

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
38 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
30 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
39 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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2answers
43 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
85 views

Can someone explain about M-theory? [on hold]

Can someone explain about M-theory? 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 ...
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2answers
55 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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0answers
49 views

Flow between two infinite plates [closed]

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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3answers
78 views

What is the relationship between entropy and work? [closed]

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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3answers
65 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
19 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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0answers
25 views

What is the maximum level of heat that can be reached? [duplicate]

Heating is what everyone knows about . But does it have any limits . How much hot can anything become?
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4answers
48 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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1answer
36 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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33 views

p=aV+b, finding Q and L [closed]

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 [closed]

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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0answers
8 views

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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0answers
36 views

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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0answers
17 views

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
81 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
97 views
+50

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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1answer
72 views
+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
50 views

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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2answers
53 views

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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1answer
44 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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2answers
34 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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1answer
44 views

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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0answers
42 views

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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0answers
17 views

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 ...