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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Why can I calculate the value of an energy quantum of an Einstein solid at half the equipartition value of the heat capacity?

(I've realized that I'm horrible at asking the right question but I believe I pinpointed what it's really about:) Apparently the energy quantum of an Einstein solid (in the limit of classical ...
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1answer
22 views

Followup to: The relation between energy quanta of an Einstein solid and the equipartition value of heat capacity

As a followup question to this question: The relation between energy quanta of an Einstein solid and the equipartition value of heat capacity and this answer ...
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3answers
51 views

Ice and liquid water interacting across a boundary

Imagine we have two thermodynamic systems, one a mass of ice and the other an equal mass of liquid water, with both at 273.16K. Each system is isolated, except that they can interact with each other ...
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33 views

The relation between energy quanta of an Einstein solid and the equipartition value of heat capacity

Consider an Einstein solid with quantized energy values $U=q\epsilon$ and $N$ oscillators. I calculated some values of an Einstein solid numerically through a function in R (at the bottom of the ...
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1answer
47 views

What are the contributions of the Non-equilibrium Thermodynamics?

I am very interested in Thermodynamics, but though it is easy to find good books and information about classical thermo, it seems that is not the same for non-equilibrium thermodynamics. I would like ...
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103 views

Why is everything colder nowadays? [duplicate]

I know that when the universe began it was incredibly hot. Ever since, it is been cooling, and nowadays the average temperature of the universe is quite close to 0 K. Is this a consequence of having ...
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2answers
134 views

Is the second law of Thermodynamics an immense tautology?

Let's imagine for a second a system that is changing constantly from one microstate to another one. It could be a given volume of a gas with its atoms moving and bouncing around, or a deck of cards ...
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2answers
151 views

Axioms behind entropy!

The concept of entropy is very ubiquitous, we learn about its uses starting from Information Theory (Shannon entropy) up to its basic definition in statistical mechanics in terms of number of ...
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19 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
31 views

Scale down model of a refrigerator

I am teaching Thermodynamics. For teaching how refrigerators work I am looking for a working model of a scale down refrigerator. This should be as close to real as possible but very small in size. Can ...
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1answer
29 views

Calculating new temperature of an object when air temperature changes

I'm trying to calculate the new temperature of an object when the air temperature around it changes, given a period of time. Basically I get periodic readings from an air temperature sensor in a ...
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2answers
27 views

Latent heat of vaporization at non-boiling temperature

The latent heat of vaporization of water is what we normally use to calculate the heat transfer that occurs at 373 K when liquid water transits to vapor phase. But there are curves for latent heat of ...
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What are the thermal properties of a “perfectly rigid” container?

can a "perfectly rigid" container be a diathermal boundary? I checked the wikipedia article for heat and read: Kinetic theory explains transfers of energy as heat as macroscopic manifestations of ...
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1answer
52 views

If you dig a deep tunnel, will the rock sublimate?

If a tunnel is dug deep inside the crust (but before reaching places where the rock is liquid), how will the enormous downwards pressure manifest itself? Will the difference in pressure ...
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35 views

Thermodynamic potentials: Demonstration [on hold]

I must prove whether the statement on bold is true or wrong. Under it there is what I tried, but it does not convince me. I use one maxwell relationship on the latest line. And I take advantage of ...
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2answers
81 views

Is Rosehip Syrup boiling in a bottle?

My wife made Rose-hip syrup and the final part was boiling it in a saucepan. While still hot she placed it in a glass bottle. To keep it sterile she plugged it with a wine-saver top and sucked out ...
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1answer
92 views

Gravity and the Second Law of Thermodynamics [duplicate]

I was wondering about the hypothetical - and apparently improbable - heat death of the Universe when I stumbled upon this seeming contradiction. A certain volume of space with a uniform distribution ...
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1answer
35 views

Calculate heat transfer out of a basement

I am thinking it should be possible to calculate heat loss out of basement based on the temperature of the walls, but am not sure how to do it (what the equations are). For example, lets say the ...
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30 views

How to solve this steady flow problem? [on hold]

Consider a steady Flow of air through a insulated porous plug. Air enters the plug at 100 kPa and 150m/s and leaves the plug at 50 kPa. Assuming air to be ideal gas and neglect potential energy ...
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32 views

A problem of thermodynamics [on hold]

A lake is covered by a block of ice 10 cm thick. The water temperature is 0ºC and -5ºC for the air above. Calculate the ice growth rate of the block dx/dt knowing that the latent heat of fusion is ...
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33 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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1answer
18 views

Variable area manometer duct

How does one measure the pressure at the end of the manometer tube when the manometer tube itself is having a variable area?
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3answers
98 views

How many volcanic eruptions would be necessary per year to neutralize global warming?

Volcanic eruptions sometimes cool the earth. How many eruptions of what magnitude, locality and type would be required per year to neutralize Global Warming?
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22 views

How powerful would a series of rail guns or bombs need to be to destabilize a hurricane?

In an effort to destabilize hurricanes by burning the necessary cold zones it has been proposed that planes drop various carbon trash on them. That seems like a minor amount of heat change over a ...
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1answer
34 views

Partial Pressure - Which solution is right?

Question: Carbon dioxide (1.100 g) was introduced into a 1.00 L flask which contained some pure oxygen gas. The flask was warmed to 373 K and the pressure was then found to be 608 mmHg. If CO2 and O2 ...
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1answer
43 views

Irreversible work

I'm having some trouble trying to find the irreversible work done by a perfect gas when expanding. I know that the reversible work is greater than the irreversible one, but how can I find the ...
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2answers
41 views

Problem regarding heat engines [closed]

We have two different set ups: A 200K brick in a 300K environment A 300K brick in a 200K environment From which one of these can you extract more work? Assume equal mass and heat capacity. Using ...
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4answers
119 views

why are the square of the components of velocity equal?

In Principles of Physics by Resnick,Halliday,Walker, when evaluating the $v_{rms}$ ,they first found $p = \frac{nM(v_x)^2}{V}$ & then substiuted $(v_{avg})^2 = \frac{1}{3} .v^2$ where $v^2 = ...
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2answers
115 views

Who invented the perfume bottle thought experiment?

A common thought experiment used to explain the second law of thermodynamics, the "arrow of time", etc. is perfume escaping from an opened perfume bottle; the perfume is likely to diffuse into the ...
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1answer
74 views

Thermodynamics for Dummies: Entropy and temperature

I do not study physics and I have never had a course in thermodynamics. I have no idea what it is about, but I am currently taking a course where we had something about entropy. Would be great if ...
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2answers
107 views

Coarse graining on measurement vs phase space (second law)

I've followed Leonard Susskinds series on "the theoretical minimum". In the entropy/reversibility episode in statistical mechanics, he explains (at least one way of) how the apparent paradox of ...
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26 views

Good explanation of phase transitions, second law of thermodynamics [duplicate]

I am looking for a good explanation (website, book, video,...) of phase transitions. I am interested in atmospheric applications (so basically condensation, etc. of water in air). I would like an in ...
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1answer
38 views

Liquid Column “Recoils” in a Sealed Cylinder When Hit by a Piston — Is it Possible?

Consider a cylinder filled partially with a liquid (e.g. water). The cylinder is sealed, and is at held at room temperature (e.g 298K). At equilibrium (or when no external disturbance is imparted to ...
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2answers
62 views

The thermodynamics of heating water in a rigid container

When the pressure on the liquid surface is less than the vapor pressure of the liquid at a given temperature, the liquid will start to evaporate. This is common sense. The problem is more difficult ...
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3answers
24 views

Is it possible for an electrical device to generate more heat than another using less power or the same?

People are claiming that a Plasma TV uses more power which explains why it uses more heat. We refer to power as wattage in this regard. Countering this, is it possible that a device can draw the same ...
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3answers
74 views

Is Fourier's law of conduction a consequence of the second principle?

In classical thermodynamics courses, entropy is often motivated by the need to justify that heat flows from high temperatures zones to lower temperatures zones: this is seen as a consequence of ...
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3answers
99 views

Zeroth Law of Thermodynamics, temperature, and ordering

In my thermodynamics course (and in other places on the internet) it is asserted that the Zeroth Law of Thermodynamics can be used to define the concept of temperature. One statement of the Zeroth ...
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1answer
28 views

Thermometer reading

I quickly plunged a room-temperature thermometer into very hot water, the mercury level went down briefly before going up to a final reading. Why?
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4answers
117 views

How to measure the energy consumption class of a home appliance? [on hold]

Some of you may be familiar with the EU energy consumption classes for domestic appliances (or equivalents in other areas). Let's say we have a domestic appliance which was made before the energy ...
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1answer
47 views

Total multiplicity and entropy of Einstein solids

This is really a question to get a little more insight about a homework exercise. 1. In my text book, the sum of multiplicities for all possible macrostates is given to be: $$\sum ...
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1answer
66 views

Are temperature increases discrete? [duplicate]

Are temperature increases ever discrete in nature, or is it a continuous variable? If a discrete case exists, is there any material that exhibits particularly strange behavior?
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1answer
73 views

Making fire using a filled water bottle

I have seen videos where a fire was started using a water bottle filled with water. I guess the bottle acts like a convex lens that converges light to a focal point to start a fire. But why does water ...
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Why is it natural to look for solutions involving dimensionless quantities?

While studying the Heat Equation, I got stuck in a statement in my book. It says: We have seen that the combination of variables $\displaystyle \frac{x}{\sqrt{Dt}}$ is not only invariant with ...
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1answer
54 views

Why is density an intensive property?

I am still trying to understand what are intensive and extensive properties. Possibly someone can give a pointer to a decent text (preferably on the web), as I am not too happy (to say the least) with ...
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34 views

Energy from the Feynman-Kikuchi Partition Function

The Feynman-Kikuchi Partition function is given as $$Z_{FK}=K_\beta \int dx \eta(x) \exp \left(-\frac{x}{\beta}\right) $$ where $K_\beta$ is a normalization constant and ...
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43 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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1answer
34 views

Capacitor-like-thing for controlling temperature of fluid?

I want to minimise the Gibbs' phenomenon like thing i.e. sudden peaks (temperature peaks here) in a container. Assume you have a cone where you want to block the transmittance of the temperature into ...
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1answer
50 views

Dark Matter as possible an explanation for Coronal Heating

It's my understanding that the mechanism behind Coronal Heating - why the Corona is so much hotter (> 1,000,000 K) than the surface of the Sun (6,000 K), and the mechanism by which the energy gets ...
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25 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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1answer
33 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. ...