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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Thermodynamics of zinc chloride to zinc

I am trying to deposit zinc metal from zinc chloride using chemical vapor deposition. But it is thermodynamically feasible to obtain zinc from zinc chloride?
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20 views

Delayed Phase Transition at Condensation of a Gas?

It is known that super heated liquids do exist, eg. when purified water is carefully heated above its boiling point. However I've never heard of subcooled gas having a temperature below its saturation ...
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502 views

How does heat pass through glass?

So infra-red and ultra-violet waves from the sun heat up the glass by conduction then it then radiates this heat to heat up a room or a car? Is that right? How would one calculate how much heat a ...
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51 views

Thermal Dynamics Conduction Comparison

I didn't have to take much physics for my advanced college degree, so I apologize if my question is painful. From reading and experience it seems that water is a better thermal conductor than air. I ...
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80 views

How do we know that the Virial Expansion exists?

How do we know that the Virial Expansion exists? How do we know that we may always write $\frac{p}{kT}$ as a power series in $\frac{N}{V}$? That is, how do we know that there exists $B_{i}$ so that ...
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77 views

Why is $B(T)\approx b(T-T_C)$ near critical point $T_C$ in Landau theory?

In Peskin&Schroeder page $270$ equation $(8.4)$ you see that they approximate the function $B(T)$ near the Curie temperature as $$B(T)\approx b(T-T_C)$$ i.e. they omit $B(T_C)$ in the Taylor ...
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107 views

Work in Newtonian Mechanics and Thermodynamics

Well, is the basic difference between the work that we learn in Mechanics and that in Thermodynamics? This is because in Mechanics, whenever work of magnitude $W$ is done on a system $S$, then the ...
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2k views

Enthalpy Change in Reversible, Isothermal Expansion of Ideal Gas

For the reversible isothermal expansion of an ideal gas: $${∆H}={∆U}=0 \tag1$$ This is obvious for the case of internal energy because $${∆U} = \frac {3}{2} n R {∆T} = 0 \tag2$$ and $${∆U} = -C_P n ...
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67 views

Law of equipartition

Law of equipartition predicts the heat capacity of gases correctly. It assumes that inter-molecular attraction in gases is negligible (which is true). But for solids, inter-molecular attraction is not ...
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60 views

Molecules of a solid [closed]

Question: Molecules of a solid : (a) are always in a state of motion (b) move only when heated (c) move because they are loosely bound (d) do not move at all My attempt: I ...
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75 views

Entropy of a chain

A chain has N segments which can be oriented in either the x or y directions. For each segment oriented along y, there is an energy penalty of $\epsilon$. We also know the end segment is at $(L_x, ...
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61 views

How many radiotherapy sessions would it take to boil one cup of water? [closed]

Context: Gray (Gy) is a unit dose used in radiotherapy. It is defined as the absorbed energy of 1J per kilogram of matter. There is a wide misconception that ionizing radiation acts by heating ...
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103 views

cooling glass of milk glass and a jar of water

When im given a steel glass of boiling milk which I cannot even touch, I used to put that glass in a jar surrounded with room-temp water and give it 10 mins. At the end, I used to find the steel glass ...
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721 views

Why does the windshield of my car freeze even if the outside temperature is above freezing? [duplicate]

Under what conditions does the windshield of a car freeze even if the outside temperature is above freezing? It is not clear whether this is related to the question why bridges freeze with ...
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517 views

Mixing of Ideal gas - Thermodynamic equilibrium

I always get confused what exactly happens when two ideal gases mix. Consider the initial situation where two gases are in a box, separated by a rigid and adiabatic wall between them. Now when the ...
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49 views

Maximising entropy when energy is shared between systems

This is a problem to do with statistical physics, and the exchange of energy when we have two microcanonical ensemble. I don't understand why there should be a minus sign in the middle, if Energy* ...
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357 views

What is the maximum theoretical efficiency of heat to electricity conversion?

I know that heat engines (heat to kinetic) are limited by Carnot cycle and that kinetic energy to electric energy conversion via standard generator reaches over 90%. However I would like to know ...
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89 views

Amount of heat required at for unit rise in temperature at different temperatures of water

In my text book, it is given : One calorie is defined as the amount of heat required to raise the temperature of water from 14.5 °C to 15.5 °C. I found out in wikipedia that this is actually ...
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42 views

Is the temperature different and or salinity different can lead to different colour of the water bodies?

I had skimming on an article about Thermocline and Halocline. How can two seas not mix? However, I am still curious on: Why the effect of Thermocline and Halocline are distinguishable based on ...
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140 views

Derivation of the Thermal Noise Spectrum

The thermal noise spectrum is given by: $$\mathcal{S}(f) = \frac{\hbar f}{2(e^{\frac{\hbar f}{kT}} - 1)}$$ This equation seems really similar to the Dirac-Fermi distribution but where does it come ...
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207 views

What would give us more heat ? infrared or microwaves?

As we know that our body is made up mostly of water and the frequency of vibration of water molecules matches that of microwaves which is the working principle of microwave ovens. When we come in ...
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255 views

Does heat increase the volume of a gas, and in turn its pressure?

Lets say you have 1 liter of hydrogen in a sealed container, at 100 psi. If 50 cm^2 of the containers surface area is heated to a 1000 degree Celsius, will the psi increase over time? What would be ...
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182 views

Is An Exploding Beer Bottle An Accurate Simulation Of A “Frost Quake”?

A Frost Quake or Cryoseism is similar to an earthquake except it is triggered by ice expansion instead of tectonic activity. A Cryoseism may also refer to the sudden movement of a glacier, but I am ...
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78 views

Thermo-couple Eelectroomotive force

I am studying thermocouples. In a text book, the author said that, the electromotive force can be written as $$ E= \alpha \theta + \beta \theta^2 \tag{1}$$ where $\alpha$ and $\beta$ are constants ...
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47 views

Transfered thermal energy to a gas with varying mass

In my physics book (and wikipedia) it states that the thermal energy transferred to an object is: $Q = c \ m \ dT$, where $Q$ is the transferred thermal energy, $c$ is the specific heat capcity of the ...
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113 views

is this heat calculation equation correct?

If I have a line of copper wire (lets say $\textrm{1 meter}$ long, $\textrm{1 mm}$ thick) and one end is a flattened disk of copper about the size of a quarter, and I apply a lot of heat to it (I'm ...
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64 views

Second law of thermodynamics and motion

The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems spontaneously evolve toward thermodynamic equilibrium—the state of ...
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63 views

Radiation pressure thermodynamic paradox

Could the radiation pressure of a black body (theoretically) perform work on the perfectly reflecting apparatus in the figure below? Assume that the block does not hinder the passage of light through ...
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149 views

How do you define a reversible path for general processes?

The equation $dS = \frac{\delta Q}{T}$ is only defined for a reversible path. Given a irreversible path we typically calculate the entropy by choosing a reversible path from the same initial to final ...
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551 views

Can a glass window protect from heat radiation?

I have been reading in this and found a statement saying : " Glass will not transmit heat radiation.". So now I am confused. If glass won't transmit heat radiation, then why do we feel hot when we sit ...
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2k views

How do you calculate the change in temperature of an adiabatic system?

I really don't even know how to start doing this problem. I understand PV=nRT and I understand that if either T, V, or P is kept constant, then the other 2 change at the same rate, and I understand ...
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74 views

Will the heat flow of Joule heat be different, if the Joule heat is dissipated in a material that has a temperature gradient beforehand?

Let us assume one dimensional heat transfer, for example a finite length wire starting at point $0$ and ending at point $\ell$. If the current passes the wire, the Joule heat $I^{2}R$ will be ...
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122 views

Are $G$, $F$ and $H$ (thermodynamics potentials) extensive quantities?

Internal energy $E$ is an extensive quantity for most systems. But energy extensivity is not valid in systems with long-range interactions, like gravity (e.g. in astrophysical systems). For extensive ...
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62 views

Tungsten Wire Heat discipation

Background Information: I'm doing an experiment in which I place a bare tungsten wire in to various liqids, to measure a coefficient $\alpha $ in the equation $$ Power Dissipated = \alpha * \Delta T ...
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187 views

Proper name for a thermodynamic process with constant internal energy $U$

Back in the day I learned that a few special thermodynamical processes have special names. For example, if one keeps $P$ constant, the process is called isobaric, if one keeps $T, V$ or $S$ ...
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418 views

Liquid nitrogen condensing oxygen out of the air

In this video, a pool of liquid nitrogen in a metal bowl can cool it enough so that oxygen from the air condenses at the bottom: ...
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68 views

Determining if a solution will boil

A piston compresses a solution of 40% $HNO_3$ in $H_2O$. If the piston breaks and the pressure is reduced from 12.0 atm to 1.0 atm: a) If the temperature of the solution is 110 degrees C, will the ...
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258 views

Why does the specific thrust of an ideal turbojet drop with increasing compressor pressure ratio?

As the pressure ratio increases in an ideal turbojet (fixed flight Mach number), the specific thrust, $\frac{F}{\dot{m_{air}}}$ rises, reaches a peak for small pressure ratios and then starts to ...
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58 views

Efficiency of the insulation of a house

I had an argument about the most cost-effective way to keep the energy bill low in the winter (here, temperature usually have an average of -20°C (-4°F)). He thinks that it's more effective to keep a ...
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75 views

Showing specififc internal energy $e$ is a perfect differential

I am reading a book on Gas dynamics and there is a small section on thermodynamics before the conservation laws of mass momentum and energy are introduced. The book says $$ p = R \rho T$$ where ...
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150 views

Calculating sum of heat transfered

I have a formula of thermal conductance heat transfer rate. Here it is: $$ Q = \lambda{S (T_1 - T_2) \over L} \Delta t $$ For my calculations I have got some constant values available $$ Q = 0.58{1 ...
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226 views

Why does time reversibility imply equilibrium in a thermodynamic system? [duplicate]

I'm reading through Kardar's Statistical Mechanics of Particles; in the section 1.5 he says: A reversible process is one that can be run backward in time by simply reversing its inputs and ...
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139 views

What the rate of heat transfer between my thumb and a surface of known dimensions and properties?

I am trying to calibrate a high speed thermocouple for measuring heat transfer rates. One of the calibration techniques I am using is sticking my thumb to the thermocouple (which is embedded flush ...
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153 views

Any closed system?

Is there any physical example of a real closed system? I am aware that the whole universe can be considered as a closed system, but I am looking for a smaller example.
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2k views

Definition of “intensive” and “extensive” properties

Today I was asked what does it mean for a physical property of a system to be intensive. My first answer, loosely speaking, was: "It is a property that is local." I was specifically thinking ...
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472 views

Calculating the ideal mixing entropy using Gibbs' entropy formula

Two distinguishable gases are in separate volumes $xV$ and $(1-x)V$ $(x\in [0,1])$ respectively, and the number of particles on each side is $xN$ and $(1-x)N$ respectively. The volumes are separated ...
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274 views

Thermodynamics in a closed room - Why does the stale smell depend on Temperature? [closed]

Why does the stale smell disappears in a crowded room if you cool it via air-condition ? What's the physics ?
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119 views

Waterflow of coolant in nuclear reactor [closed]

The generator in a nuclear reactor delivers 580 MW electric power. a) How much TWh electrical energy is delivered yearly if the reactor runs only 70 % of the time? b) What flow of coolant ...
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100 views

Evidence of atoms from Dulong–Petit law?

All materials have same molar specific heat, cf. the Dulong–Petit law. Is it an evidence of atoms? What other examples are there for atomic theory?
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7k views

Thermodynamics: Are pressure and temperature enough to calculate enthalpy?

From the chart above, it looks like it is possible to calculate enthalpy from just pressure and temperature. After a few hours of Googling my question, I'm not able to find anything helpful. My ...