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 does maximal entropy imply equilibrium?

From a purely thermodynamical point of view, why does that entropy have to be a maximum at equilibrium? Say there is equilibrium, i.e. no net heat flow, why can the entropy not be sitting at a ...
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458 views

Why does blowing on someone who is wet feel colder than on someone who is dry?

The title says it all. If I'm standing in the wind and I'm wet, I feel much colder than when I'm dry. This is true no matter how warm or cold the water. Why is this?
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371 views

Why do moving particles emit thermal radiation?

While answering another question about heat in an atom, the discussion in the comments led to the question of how heat is related to thermal radiation picked up by infrared cameras. The answer is that ...
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Why are the virial coefficients functions of temperature only?

I have read in multiple places that the virial coefficients in the virial equation of state, $Z=1+{B \over v}+{C \over v^2}...$, are functions of temperature only and are independent of pressure (or ...
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Can a water bubble be frozen into ice bubble?

To maintain the surface tension which formed our original bubble (in order to keep the bubble from breaking), we may change the temperature/pressure of air on both sides of the bubble varyingly, with ...
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Radiation– white vs black house, hot or cool?

In my book's thermodynamics chapter, it says that an "object that radiates heat faster also absorbs heat faster. This means that an object that is a more efficient radiator comes to equilibrium ...
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200 views

How to derive a physical model of temperature above the earth surface?

At a point on the surface of the Earth, if I go straight "up" a distance $z$ (radially outward from the Earth), I'd observe a temperature profile $T(z)$. The conventional wisdom from the meteorology ...
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305 views

Gas kinetic representation of trans-critical conditions

From a molecular point of view, can we think of the super-critical conditions as conditions where T and p are large enough that the collisions of gas molecules are frequent and powerful enough to ...
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296 views

How much energy from extreme coldness?

Let's say I have: 1: one mole of extremely cold ideal gas 2: unlimited amount of ideal gas at temperature 300 K 3: one ideal heat engine Can I generate for example 1 MWh of mechanical energy using ...
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168 views

Any open areas to work in non equilibrium thermodynamics for a Phd student? [closed]

I see that many papers written on fundamentals of thermodynamics(theory) nowadays are by some old professors somewhere(there may be exceptions). Most active young faculty don't seem to be seriously ...
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657 views

Maximum Principle vs. Minimum Principle in Non-equilibrium Thermodynamics

Prigogine's Min. principle states that in steady-state non-equilibrium systems the entropy generation rate is at a minimum, i.e., a system will seek a steady-state that has min entropy generation. ...
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602 views

Why is temperature constant during melting?

This is an elementary question but I do not know the answer to it. During a phase transition such as melting a solid to a liquid the temperature remains constant. At any lower temperature the heat ...
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Recommendations for Statistical Mechanics book

I saw Book recommendations No reference to Statistical Mechanics there. I learned thermodynamics and the basics of statistical mechanics but I'd like to sit through a good advanced book/books. Mainly ...
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523 views

2$^\text{nd}$ law of thermodynamics: equivalence of statements

Consider the following statements: Clausius statement (according to Wikipedia): No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of ...
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104 views

Why doesn't gravity ruin satellites?

Recently I watched a documentary about Io, a moon around Jupiter. Io has volcanic activity even though it is small and can't retain heat well because gravity from Jupiter and a nearby moon cause it to ...
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105 views

Doubts about the ideal gas law

EDITED AND SOLUTION: In fact my stupid mistake was to take the wrong value for my $P_1$ and I was getting an 1.2998 that finally is a 1,9178 within just a difference about 7%. So at the end they are ...
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303 views

Is there a phase transition between a gas and plasma?

Does a phase transition occur as a gas is heated to create a plasma? If so, is this a first or second order phase transition? Also, does the presence of a phase transition depend on the pressure or ...
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442 views

When should I take wine out of the fridge - transient heat transfer problem

I am hosting a dinner tonight for which I'll be serving white wine (Riesling to be more specific). Generally white wine is best served chilled (not COLD!) at around ...
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Why do reversible processes not increase the entropy of the universe infinitesimally?

The book Commonly Asked Questions in Thermodynamics states: When we refer to the passage of the system through a sequence of internal equilibrium states without the establishment of equilibrium ...
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What is the relationship between Energy, Entropy, and Information?

What is the relationship between Energy, Entropy, and Information? I read this - What Is Energy? Where did it come from? - and the top answer says that 'energy' is an abstract number that is a ...
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567 views

Microwave oven + water: dielectric heating or ion drag?

When you place a water or food in a microwave oven, it heats. Which process commits more energy to that: dielectric heating, or ion drag i.e. resistive heating? AFAIK, in distilled water (which is a ...
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291 views

Is an entropic force an actual force that can be explained as a fundamental interaction?

Fundamental interactions, such as electromagnetism, the strong force, the weak force, and possibly gravitation, all have something in common: They can be described in terms of relativistic quantum ...
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135 views

Would the temperature of a gas change when accelerated in a train?

I was thinking about a situation where some gas is enclosed inside a container and kept in a train at rest. The train accelerates, gains a maximum speed and then suddenly stops. Would the temperature ...
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353 views

Postulate of a-priori probabilities

In Statistical Mechanics, we often postulate that for an isolated system, the phase-space density of all accessible microstates (i.e all microstates consistent with the energy) is the same. This is ...
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relativistic spaceship, CMB radiation and thermodynamics

Scenario: a spaceship is travelling at a high fraction of $c$. The interstellar gas and CMB radiation has blueshifted significantly and we are facing a possible melting of the front radiation shield! ...
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481 views

Wick rotation and the arrow of time

It is well known that we can switch from a statistical system to a quantum mechanical system by a Wick rotation. Has this rotation some implication on the way the time flow? namely, this is an ...
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148 views

Can we detect whether food has previously been heated in a microwave oven?

An acquaintance told me that she refuses to eat microwaved food because she read that the microwave changes the molecules of the food somehow. Her statement is vague and her sources are dubious but I ...
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How to obtain the free energy of the canonical ensemble in Euclidean general relativity?

If the gravitational field couples with matter fields, such as a charged scalar field, I know the partition function of the grand canonical ensemble naturally relates to the path-integral expression ...
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Is a venturi pump feasible at very low pressure?

I need assistance (or experience feedback) in estimating if a Venturi pump would work at low pressure. A boiler under vacuum (10% atmosphere) will produce steam (at a given speed depending on the ...
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Is it possible to have annealing without creep?

Annealing can repair a material by allowing atoms to find the minimum energy state; since solids have a surface tension this process will allow cracks to fuse and reverse fatigue. However, annealing ...
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Should I heat my room when I'm not here, energy-efficiently speaking?

I was wondering as it's getting cold : is it better for my electricity bill to shut down completely my (electric) heater during day, and to turn it on again when I come home (then it will have to heat ...
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Is it theoretically possible to reach 0 kelvin?

I'm having a discussion with someone. I said that it is -even theoretically- impossible to reach 0K, because that would imply that all molecules in the substance would stand perfectly still. He said ...
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Why does hot oil explode when pouring water on it?

I am puzzled to know, What is the reason of hot oil make sound and explode when we pouring water on it?
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Why does microwaved food get cold faster

My evidence is entirely anectodal and non-scientific, but I've noticed food gets cold faster when it's been heated in a microwave instead of a stove. Is this true? And if it is, why does it happen?
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The difference between heat and temperature

So as I understand it, heat energy of an object is the SUM of all the kinetic energies of the molecules of the object (upto constant factor). The temperature on the other hand is the AVERAGE of the ...
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What is the meaning of following expresion $C=\frac{\delta Q}{dT}$ mathematicly

Our professor raised the following question during our lecture in Statistical Physics (even so it's related to Thermodynamics): Many text books (even wikipedia) writes wrong expressions (from ...
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experimental technique for measuring temperature of an ant

I am taking a course on thermodynamics. I have a question from my text(halliday & resnick,physics-1). They asked me to measure temperature of an ant or an insect or a small body,like a small ...
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Could a sleeping bag be warmer if you are naked inside?

I have heard conflicting theories about the best way to keep warm in a sleeping bag in the winter. Some people say you should bundle up in your sleeping bag and another theory says that you should be ...
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What causes hot things to glow, and at what temperature?

I have an electric stove, and when I turn it on and turn off the lights, I notice the stove glowing. However, as I turn down the temperature, it eventually goes away completely. Is there a cut-off ...
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191 views

Does diamond dust conduct heat as well as diamond?

Diamond is one of the best thermal conductors you can get. If the diamond is crushed into dust and spread out over a flat surface, but still held fairly compact (for instance in a small petri dish), ...
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262 views

Solidification by the application of heat

When you add heat to a liquid (or a fluid), can it be solidified? If not, why in the world does an egg's stuffs become solid (or at least no more a liquid) when you 'boil' it in water?
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what is the basic form of the 'fire'? [duplicate]

Possible Duplicate: Is fire matter or energy? What is the basic form of fire? physics defines every entity by a basic form either solid or liquid or as a gas, example: water is liquid, ice ...
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507 views

Can temperature be defined as propensity to transmit thermal energy?

I was recently surprised to learn that defining temperature isn't easy. For a long time, it was defined operationally: how much does a thermometer expand. Also surprising, temperature isn't a ...
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Why are lasers inefficient?

Why are lasers inefficient? Is it because of the heat lost during lasing? Why couldn't there be thermocouples or turbines in parts of the cooling circuits to extract something out of that heat?
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1answer
107 views

Heat engines and “Angular momentum” engines?

We know that the theory of heat engines is that, if you accept the second law of thermodynamics, $\Delta S > 0$ then you can define temperature using $\frac{1}{T} = \frac{\partial S}{\partial E}$ ...
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550 views

Are negative temperatures typically associated with negative absolute pressures?

Negative temperatures and negative absolute pressures are both possible in physical systems. Negative temperatures arise in (for example) populations of two-state systems, which have a maximum amount ...
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573 views

How long will my fridge magnet stay attached to my fridge?

I have a 500 gram neodymium magnet. It is stuck to my fridge. With the constant pull of gravity trying to pull it off how long would it stay attached to fridge? For arguments sake lets say my fridge ...
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Can you make ice red hot?

This video clip allegedly shows an otherwise unspecified ice cube that turns red hot (and burns) due to induction heating. Can somebody explain how this works?
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Why did my liquid soda freeze once I pulled it out of the fridge and opened it?

This isn't a duplicate to "Why did my liquid soda freeze once I pulled it out of the fridge?". My question is why soda froze after it was opened. Opening a can or bottle seems to have a larger effect ...
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620 views

What happens if you connect a hot resistor to a cold resistor?

Kind of an extension to this question: If you heat up an object, and put it in contact with a colder object, in an ideal insulated box, the heat from one will transfer to the other through thermal ...