This is almost by definition. Recall that the definition of modular hamiltonian $\mathcal{K}$ is $$\rho_A=e^{-\mathcal{K}} \tag{1}$$ where $\rho_A$ is a reduced density matrix associated with ...

In a closed container at constant temperature, the humidity will eventually reach 100% when there is any liquid water present.What happens when you have temperature differences? When you heat up air ...

To add on to what the other answers said, another thing to consider is what will happen to the bottle temperature as the water condenses on it.Condensation releases heat. If you're trying to sense ...

Existing answer by Paulo Rodriguez is correct, and one might add: condensation is a remarkably sensitive indication of temperature when conditions are still. If the condensation is going to happen at ...

Droplets form when the air inside the bottle cools below the dew point, and the surface provides a place for that moisture to collect.The side that was kept in complete darkness stayed consistently ...

It's important to remember that water is a good conductor of heat. If a thermometer is fixed statically against a flowing stream, then the impact of water molecules does generate heat that could be ...

In statistical physics we consider the system in its center-of-mass reference frame, so that the velocities of the molecules that are relevant for temperature are those in this reference frame, and ...

You are on the right track, and I believe that you should be concerned with which reservoir the heat is transferred from. In the Reverse Carnot Cycle, the gas only interacts with the cold reservoir ...

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During heating, the working medium is not in contact with the hot environment. Similarly, during heat rejection, the working medium is not in contact with the cold environment. Below follows a short, ...

Callen's book has the significant merit of presenting a reasonable account of an axiomatic approach to Equilibrium Thermodynamics, following the path laid out by Tisza (Tisza, L. (1961). The ...

Callen's postulate mixing definition of equilibrium states with internal energy seems quite strange to me.An equilibrium state is defined by the presence of thermodynamic equilibrium: constancy of ...

When water flows down a constant slope, it keeps a constant average speed. Potential energy turns to kinetic energy and then to heat. This does heat the water.A typical speed for flowing water is ...

You can do it either way.The temperature is not frame-independent.If you define a frame where a particular fluid portion is at rest, your temperature calculation will exclude the bulk motion and you ...

Yes and no, the order parameter is subjective in the same way the phase is subjective. We come to understand phases by observing systems and noticing certain features about them that are different, we ...

Gas constant is $R=N_Ak_B$, where $N_A$ is Avogadro number and $k_B$ is Boltzmann constant. This is why a more handy form of the gas law is$$PV=nRT\rightarrow PV = Nk_BT,$$where $N$ is just the ...

You would probably agree that writing an equation $3 \text{ m} = 25 \text{ kg}$ is nonsense. As both equation sides differ numerically and dimensionally.You are trying to do similar thing, removing ...

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Like most dimensionful constants in physics, this one is simply a matter of the units. You could certainly get rid of the $R$ by choosing other units besides SI units. So if you defined a new unit of ...

There are actually two reasons:Thermal conductivity. Metals conduct heat better than most other materials which can be quantified as how much energy flows from one face to another face of a a 1m^3 ...

To make is simple: The sun light has a mean temperature of the sun surface as can be observed in a sun power plant with focusing mirrors.The equilibrium temperature of the surface of a body is given ...

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By "left outside", I presume you mean "left in direct sunlight". Metal just outside on a hot day but not in the sun usually doesn't feel significantly warmer to me. Because as ...

For a single phase at constant temperature, application of the fundamental relation $dU = T\,dS-P\,dV$ yields$$\begin{align}\left(\frac{\partial U}{\partial P}\right)_T&=T\left(\frac{\partial S}{\...

A proof that entropy cannot decrease in an isolated system.We consider a system and take it through a cycle from state A to B to C to A,where:A,B,C are each equilibrium states. A and B have the ...

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I'll try to complement the already excellent answer by @naturallyInconsistent with a more comprehensive discussion from the mathematical point of view, and a purely thermodynamic argument, from the ...

The rigorous mathematics of classical thermodynamics only works in the thermodynamic limit, which, amongst other requirements, require that $N\to\infty$This is also the limit in which all the finite ...

Every branch and aspect of science starts out by making approximations and simplifications in order to make progress. Elementary particle physics, with things like the fine structure constant and $g-2$...

It contains dearomatised kerosene. Liquid paraffin has a similar density. I don’t know how accurate the density needs to be to the original liquid though. The amount in the new container might ...

The step $\Delta Q_{\mathrm{irrev}} = \Delta H$ is not generally valid for anarbitrary irreversible process. It holds only when the transformation isquasistatic and isobaric, so that the system ...

The piston will continue moving and the gas volume will continue increasing. Eventually, the piston will reach a maximum displacement, stop, and then reverse its direction, leading to oscillatory ...

1 - What is "natural" about $U(S,V,N)$ compared to $U(T,N)$ and $U(p,V)$?2 - Can I derive the expressions for $U(T,N)$ and $U(p,V)$ from $U(S,V,N)$?3 - Can I derive $U(S,V,N)$ from $U(T,N)$...

this is basically right. However, there is a transient regime at the start of the pumping during which the PARTIAL pressure of water vapor may decrease possibly at or below the 3.16kPa level: at this ...

This question is not as trivial as some comments make it seem. Let's break it down:If you review the 0th principle of thermodynamics, in its most usual formulations it starts by defining a magnitude ...

You need to implement a plan on the lines of HAACP (Hazard Analysis and Critical Control Point) See Govt. web siteYou need to track temperature and times at which these products are kept. (Not ...

This is not intended to be a complete answer, but the accepted answer seems to miss some key physics, so I might fill in a few gaps.Suppose a small bubble forms. Then the vapor in the bubble is at a ...

Your question is unclear. I believe these graphs are plots for the interaction potential for two electric dipoles, with the distance being the inter-dipole separation. When the potential is examined ...

The freezing point of water is $0^oC$. The freezing point of saturated salt solution is about $-18^oC$. When salt is thrown onto solid ice some of the salt dissolves thus lowering the freeing point of ...

Adding salt lowers the freezing/ melting temperature of ice. Throwing salt on an icy road will melt the ice unless it is very, very cold. For the same reason salty ice keeps things cooler, as its ...

No, an ideal gas cannot reach negative temperature. In order for a system to reach negative temperature, their needs to be some upper bound on the energies the particles can have. The particles in an ...

If by mass you mean the ADM mass$$\rm M=\frac{2 m^2}{\sqrt{4 m^2-a^2}}$$where $\rm m$ is the irreducible mass the answer is no, since adding spin $\rm a$ also increases $\rm M$ even if $\rm m$ stays ...

Wait a sec! Water will freeze in a vaccume at ambient temperature. why won't it stay frozen in a vacuume? And some of this don't jive. You can prevent the water from boiling out by putting it in a ...

If you open the can it will cool rapidly if you reduce the pressure, but of course you will lose all the fizz. (cooling by latent heat of evaporation of the water.) Otherwise as the other answers ...

The identification of the grand potential with $- \gamma A$ (I would refer to leave the symbol $T$ for temperature) is not only a matter of dimensional analysis. Indeed, for a 2D simple system, the ...

The issue is that you don't define the "0" in Fahrenheit. Going from 10 degrees C to 20 degrees C only represents a 100% increase if you assume that 0 degrees C is the baseline, e.g. (20-0)/(...

Callen's approach aims to present Thermodynamics with a formal approach, based on some postulates implicitly defining the role played by some physical quantities. From such a point of view, all we ...

I would say that a "machine" can be defined in terms of its action on a system, i.e., a machine changes the thermodynamic state functions of a system so that the system is no longer closed. ...

Entropy is only postulated to exist for equilibrium states. In a non-equilibrium state, there is no entropy to speak of.There are idealized processes called quasi-static processes. In such processes, ...

Percentage changes are often extremely dubious, particularly for temperaturePercentages in general are often dubious and hard to intuit because the way they are discussed and reported often omits key ...

I will assume there is a single black hole in the universe, in the sense all other black holes are too far away to matter (since you proposed using neutron starts to "tug" at the black hole, ...

You are right to question this feature of the standard Hamiltonian for free EM radiation. Textbooks talk about how quantization solved the UV catastrophe, but then some of them also use use the ...

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No, it is not really meaningful in Celsius or Fahrenheit. The reason is that they are interval scales and not ratio scales. Meanwhile Kelvin and Rankine are ratio scales, so talking about a 15% ...