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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Does the molten salt used at projects such as Gemasolar need to be replaced after some cycles?

The project at Gemasolar uses molten salt to store heat. This heat is then used with water to drive steam turbines. Over time does this kind of repeated heat/cold cycle make the molten salt a less ...
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1answer
175 views

Temperature and latent heat

Building a bronze stature we make a mold and pour in the liquid bronze when the bronze hardens we remove the mold. The mold is made of 3 Kg of steel and the statue has a mas of 1 Kg. The specific ...
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2answers
2k views

Why I will feel colder when I get out from a swimming pool? [duplicate]

A friend of mine told me that because water heat capacity is higher. He also mentioned that it was similar to alcohol on skin effect. Assume that there are 3 situations. 1. I did not get wet 2. I got ...
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1answer
150 views

Determine the flow and amplitude equation for thermal energy (with Del operator)

It is a question vector calculus and Maxwell's laws. I put it this way. Let's say, we are working in a $3$-Dimensional space ( e.g $x\cdot y\cdot z = 4\cdot3\cdot2$, a certain room/class of that size ...
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1answer
379 views

Cause of sea ice freezing during an upwell event

One of the Episodes of BBC's documentary Frozen Planet describes an upwell phenomenon in the Antarctic Ocean. I am trying to understand the cause of seawater freezing when this upwell occurs. Liquid ...
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2answers
3k views

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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1answer
62 views

What is the average total heat incident on Earth's surface each hour?

Just what the title states Some part or the other of this Globe faces approximately towards the Sun during each 24 hour period. What is the total amount of heat (in calories) incident on average ...
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2answers
308 views

Density of states via a Laplace transform

Is this formula correct? $$ \frac{-1}{\pi}Im\int_{0}^{\infty}\!dt~\exp(Et)\Theta (t)\exp(i \epsilon t) ~=~ \sum _{n}\delta (E-E_{n}), $$ $$ \Theta (t)~=~ \sum_{n}\exp(-tE_{n}) ,$$ and I have used ...
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53 views

What would happen to Earth if the Sun suddenly disappeared? [duplicate]

Possible Duplicate: If the earth left the solar system for interstellar space. How long would it take for atmosphere to freeze Suppose the Sun simply vanished, what would be the ...
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2answers
141 views

May molecules of ideal gases have an inner structure?

The following question is probably very elementary: whether molecules of ideal gases may have optic properties? As far as I understand, when one discusses optic properties, one assumes that molecules ...
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3k views

Why does Joule-Thomson expansion of a gas do no (external) work?

I understand one of the benefits of the Hampson-Linde cycle is that there are no cold-side moving parts, but isn't one losing an awful lot of energy in the throttling process? There must be something ...
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2k views

Why did my frozen water bottle explode when I opened it after it defrosted a bit?

Last night I filled a 20 fl oz bottle (http://www.thenibble.com/reviews/main/beverages/soft-drinks/boylans-mash.asp) with lukewarm water from my tap. I filled the bottle pretty much to the brim, ...
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1answer
225 views

Man on treadmill and energy/mass conservation

Suppose we put a very obese man inside a large air tight isolated room with a treadmill and he runs on the treadmill for 24 hours and at the end of the day he sees his weight has come down (mostly ...
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1answer
936 views

How to calculate specific heat capacity of an alloy

I have done an experiment in which I measured the specific heat capacity of a coin. I would like to compare the results to the actual value. I have found out that the coin is made of Cupronickel alloy ...
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2answers
39k views

How can a wooden spoon be used to prevent water from over boiling?

This is an image I found via StumbleUpon Does this actually work? If so, why?
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1answer
257 views

Loschmidt's paradox - really a paradox? [duplicate]

Is Loschmidt's paradox a paradox even today? In other words, is the paradox resolved or not?
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261 views

Second Law of Thermodynamics, heat and quantum-level explanation

I heard somewhere that the second law of thermodynamics is stating that some heat (energy) becomes unusable for work (at the scale of the whole universe). Why is it like that? Can't heat be converted ...
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1answer
998 views

Do materials cool down in the vacuum of space?

Do materials cool down in the vacuum of space? If yes, how does it really work?
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56 views

upper bound for the Kelvin scale [duplicate]

Possible Duplicate: Why is there no absolute maximum temperature? On the Kelvin scale, absolute zero represents the temperature at which there is no thermal motion. Consequently, speaking ...
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3k views

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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1k views

What is the insulative value of water?

I am having a hard to finding what the R value of water is. I am trying to compare it to styrofoam (which has an R-Value of 5). EDIT Based on the assumption that water has an insulative property, ...
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1answer
1k views

Heat of vaporization of water - dependence on relative humidity?

Does the heat of vaporization of water depend strongly on the relative humidity of the gas into which it evaporates? Some context: If we want to calculate the dew point of water, we find the ...
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3answers
232 views

What are some creative illustrations of the nature of dissipative forces?

I'm teaching a conceptual introduction to physics for American 13-15 year old students this summer. One of the main ideas I want to hit on is the relationship between energy conservation, ...
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1answer
495 views

Wind Turbine Impact

OK, I'm not sure this is not a silly question, but here goes. I've often wondered what the impact is of wind turbines on the weather. My question is, since wind turbines transform wind energy into ...
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1answer
906 views

Ideal gas with two kinds of particles, Grand canonical partition function

Consider an ideal gas contained in a volume V at temperature T. If all particles are identical the Grand canonical partition function can be calculated using $$Z_g(V,T,z) := \sum_{N=0}^\infty z^N ...
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367 views

How does the entropy of a system change when the amount of substance changes?

I am thinking of a closed system consisting only of an ideal gas. Suddenly, the amount of substance of the gas changes. No other property of the system shall change. How does this affect the entropy ...
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703 views

Which formula for entropy is correct? (OR Is the fundamental thermodynamic equality always right?)

Quick question, in the lecture notes to a thermodynamic course I'm taking, $$d\underline{S}=\frac{d\underline{U}}{T}+\Big(\frac{\partial P}{\partial T}\Big)_{\underline{V}} d\underline{V}$$ But ...
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554 views

Entropy increase and end of the universe

While taking thermodynamics our chemistry teacher told us that entropy is increasing in day by day (as per second law of thermodynamics), and when it reaches its maximum the end of the world will ...
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2answers
413 views

How can one feel cold without touching it?

Let me explain. My shower is inconsistant in how hot it gets. Whenever I turn on the shower, I always put my hand really close to the water, but not touching it, so I can feel the heat radiate from ...
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473 views

Heuristics for specific heat capacities of solids

A didactic question publish in The Physics Teacher (http://tpt.aapt.org/resource/1/phteah/v41/i1/p8_s1) asks which will melt more ice: 100g of metal at 100C or 100g of wood at 100C. (The particular ...
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2answers
1k views

Specific heat capacity

Which of two objects at the same tempreature can cause more intense burns when you touch it: the one with the greater specific heat capacity or the one with the smaller specific heat capacity and why? ...
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1answer
285 views

Wasn't the Hawking Paradox solved by Einstein?

I just watched a BBC Horizon episode where they talked about the Hawking Paradox. They mentioned a controversy about information being lost but I couldn't get my head around this. Black hole ...
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2answers
173 views

Using CO2 to air condition a room

I'm trying to determine how much dry ice or liquid nitrogen I would need to cool 3300 cubic feet, about 90,000 liters of air, from about 100F (37.78C or 310K) to about 90F (26.67C or 299.81K). I'm ...
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0answers
43 views

What is the fluid approximation for BCS action?

For a system with free fermion gas at finite density (i.e. free Dirac action), we have an ideal fluid description with rho, p, n. What is the fluid description for BCS action? Suppose we have a box ...
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2answers
588 views

What causes a Phase-Transition

A phase transition occurs when for example, heat is applied continuously to a liquid and after a certain time it converts into a gas. How does this process work in detail? Is their a chain reaction ...
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2answers
191 views

Why is latent heat required?

Why is latent heat required for a system to change its state? (I.e. liquid water to ice) Why the "extra" energy?
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3answers
540 views

Thermodynamics of cooking rice

The question is whether (1) cooking rice in a pot of boiling water for an hour and then leaving the pot (of water and rice) to cool to room temp heats my house the same amount as compared to (2) just ...
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1answer
1k views

What is the meaning of pressure of a solid?

Currently I'm taking an introductory course on thermodynamics. I've got a problem with understanding what is the meaning of pressure of a solid body. The question arose when I looked at phase diagram ...
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1answer
175 views

Amount/flow rate of N2 needed to cool substrate

I'm trying to cool a substrate inside a vacuum chamber with liquid nitrogen. The substrate holder is a block of copper suspended from the top of the chamber via nylon screws (for thermal insulation). ...
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1answer
140 views

heat of a laptop when placed on a table, when placed on a pile of books and when placed on a bed [closed]

I heard somewhere that it is dangerous to place a laptop on a bed. The reason given was that placing the laptop on the bed blocks (assume that the laptop does not have sideway fans - it only has air ...
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1answer
511 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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3answers
233 views

Slow thermal equilibrium

I have a question which is inspired by considering the light field coming off an incandescent lightbulb. As a blackbody radiation field, the light is in thermal equilibrium at temperature $T$, which ...
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3answers
401 views

Proof of existence of lowest temperature $0 K$

Im mathematics there is a concept of infinity meaning that whenever you pick a number and say that it is the smallest/Largest there is a way to further reduce/increase that number by ...
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1answer
1k views
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166 views

Is a low-current electrical arc harmful to humans?

I've heard that electrical flux non-destructive particle testing machines are considered safe because they use less than 2 amps. I have seen an arc created between two objects do considerable damage, ...
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1answer
593 views

Greatest volumetric heat capacity

Is there any substance with bigger volumetric heat capacity than water? According to this table water has the biggest known VHC. But I can't believe that in the 21. century we have no special material ...
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170 views

What kind of phases nanoparticles have (gas-solid-liquid)?

If a phase transition requires a number of particles that is in the TD-limit, can nanoparticles (~10 atoms) have phase transitions? What kind of phases and transitions nanoparticles have?
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3answers
339 views

How many particles is needed to observe a phase transition?

This is a question that was rised when we were discussing "what is melting actually". How many particles you need to form a liquid or solid. I have some remarks to point out what I want to know. Q: ...
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1answer
519 views

Thermodynamics, bullet fired into ice

I'm beginning to study basic thermodynamics and I want to solve this exercise: It fires a lead bullet from $3g$ to $30^oC$ with a speed of $240\frac{m}{s}$ to a block of ice at $0^0C$. How much ice ...
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192 views

Entropy of a black hole can be zero?

Black holes are one of highest density objects in the universe. Because of this high density(m/v) more matter is highly compressed in a very small volume( i am guessing that molecules cant freely move ...