# Questions tagged [thermodynamics]

Covers the study of (mostly homogeneous) macroscopic systems from a heat/energy/entropy point of view. Consider also using tag: [statistical-mechanics].

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### What about the grand canonical ensemble allows you to use it to describe quantum gases as compared to the canonical ensemble?

Probably an obvious question but this is my understanding so far: Ideal classical gas - gas where occupancy of an SPS <<1. Ideal quantum gas - cold dense gas where occupancy of SPS can be ...
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### Increasing thermal efficiency in cooking pasta

Odd question, I know, please don't bash me. Hopefully somebody can help me get a better understanding on this matter. Pasta is usually cooked by dropping it in boiling water (either salting water to ...
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### What are intuitive definitions of the 4 thermodynamic potentials?

So out of the 4 thermodynamic potentials only the internal energy seem to make intuitive sense to me. My understanding of enthalpy is that it is a state function which represents the total heat ...
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### What is meant by the temperature of an atom? [duplicate]

Does it make sense to ask 'what is the temperature of an atom?'. Why not?
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### Ideal gas cycle efficiency in $p$-$H$ diagram [closed]

We have a thermodynamic cycle of an ideal gas in a $p$-$H$ (pressure-enthalpy) diagram with known temperature $T_{1}, T_{3}$ and pressure $p_{1}, p_{3}$ (see the picture below). What is the ...
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### Confusion with work done in isochoric process

So recently I've come up with this thought In an isochoric process, many books state that the work done is zero because there is no change in volume i.e. the gas isn't expanding nor it is contracting....
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### How long will it take for a Schwarzchild Planck mass BH to evaporate? [closed]

My late-night calculations for the question "how long will it take for a Schwarzchild Planck mass BH to evaporate" predict 4.7 septillion years. I'm sceptical. Are my calculations true, according to ...
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### About Feynman's treatment of entropy

Feynman said in this chapter that if a system absorbs (rejects) an amount of heat $d Q$ at a temperature $T$, then we say the entropy of the system increased (decreased) by an amount $dS=d Q /T$. And ...
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### Conceptual block on energy transfer [closed]

I recently posted a question about energy transfer in oblique elastic collisions between equal mass balls, asking how much energy the slower ball can transfer to the faster ball. The correct answer ...
This is from a course in statistical mechanics, specifically the derivation of the Maxwell-Boltzmann distribution. We have an integral over the momentum space $$Z = \frac{V}{(2\pi \hbar )^3}\int d^3p ... 0answers 14 views ### Function Of A Constant Volume Gas Thermometer Concerning the mechanism of a constant volume gas thermometer, I was wondering how the adjustment of the second tube upon the open side increases the pressure; specifically, I possess knowledge of how ... 0answers 17 views ### reverse osmosis membrane We are second year cram schoolers , we are currently working on a project tackling water desalination by reverse osmosis and are required to do an experience. During the process, we encountered some ... 2answers 74 views ### Can regular air conditioner be used as heater? [closed] In winter season, the normal room temperature is generally 6 to 10 degree Celsius, if the air conditioner is working at 25 degree Celsius will it be working as a heater, making the room warm (relative ... 1answer 75 views ### Surface temperature variation with distance [closed] So here is the question I'm troubling with: We estimate that the temperature varies approximatively with that relation:$$T(x,y)=T_0+\Delta T_0\mathrm e^{-\oslash(x,y)}$$Where \oslash(... 0answers 23 views ### Query about maximum temperature you can raise a block in an isolated system of 3 blocks [closed] Set up: Consider an isolated system of 3 blocks: 1,2 and 3. At temperatures 100K , 300K and 300K respectively. The blocks all have identical properties other than temperature, i.e specific heat ... 0answers 17 views ### Does vapor latent heat depend on temperature? [duplicate] Adding energy to water makes it's temperature increase. This continues until it reaches 100 °C (at 1 atm) when it turns to vapor with a vaporization energy of 2257 kJ/kg. But if we lower the pressure ... 1answer 90 views ### After I pour a cup of tea, I can't drink it for 10 minutes. Will it stay warmer if I add the milk at the start, at the end or does it not matter? [duplicate] So preface, I work in engineering so I'm familiar with the basic principals of most fields in physics, but specialise in Civil Engineering so my knowledge of thermal physics is poor and I haven't ... 1answer 18 views ### Second-order partial derivative of Helmholtz Potential So the lecture notes to my thermodynamics course contain this relation:$$\left(\frac{\partial^2F}{\partial T^2}\right)_{V,N}=-\frac{1}{\frac{\partial^2U}{\partial S^2}}$$With no further explanation ... 0answers 34 views ### The first law of Thermodynamic in curved space As we know, the first law of thermodynamic is  dE=TdS-PdV+\mu dN . is it true for a generic metric? what is the covariant form of this equation? for example, I think chemical potential and number ... 0answers 32 views ### Grunesian Parameter vs. Effective Debye Temperature Both the grunesian parameter and "effective" debye temperature account for changes in lattice due to thermal expansion. Does this mean both can be used interchangeably? In other words, If I use an "... 0answers 30 views ### Can anyone give python code to solve TOV equation? [closed] an anyone give python code to solve TOV equation? 2answers 53 views ### When we push on a wall, can we say work is being done on the atomic particles in contact with our hand? Since textbooks say work is act transfer of energy, it led me to think of the following assumption: Work is being done on the the atoms in the wall, in contact with the hands, when we push (hard) ... 0answers 32 views ### Sun as a black body [closed] consider the sun as a black body in 6000'Kelvin and Diameter of 1.4 *10^9 meter .which is 1.5*10^5 meter far away from the earth. a)find the Irradiance on the earth's surface. b)if the earth's ... 1answer 39 views ### Entropy increase after the Big Bang? I'm trying to understand the increase of entropy just after the big bang. The way i see it going from a "soup" of particles to organized and ordered sytems like solar system, galaxies and clouster of ... 0answers 12 views ### Acoustic velocity of ideal Boltzman, Bose and Fermi gasses [closed] compare the acoustic velocity of Maxwell_Boltzman and Fermi_Dirac and Bose_ Einstein ideal gasses. this is our home work for statistical mechanics and we are studing the book of Pathria the 7th ... 0answers 30 views ### Vacuum as blackhole supersolid? [closed] If the vacuum is a super-fluid, would the infinite vacuum energy that is nonphysical to us come into play thus making all portions of the background have infinite energy at initial expansion? So Would ... 1answer 51 views ### Restricted thermal expansion [closed] Imagine a metal rod of length l with mass m. How would it expand upon a temperature difference of \Delta\vartheta with an expansion coefficient of \alpha when there are two forces F_1 and ... 1answer 32 views ### What is a condensate/ the act of condensating? We talked about the Bose-Einstein-Condensate (BEC) in our thermodynamics lecture and are discussing superconductivity in the condensed matter lecture where we also talked about a condensate ... 1answer 46 views ### Determination of the thermal resistance of a molding tool with cooling channel This is a section of cooling channels in injection moulding tools. I have tried to calculate the thermal resistance in this section with 2 methods, one analytical and one numerical. analytical ... 2answers 70 views ### Which one is more efficient: a heater or a cooler? I know that in an ideal case, both a heater and a cooler would be Carnot engines. Assuming that the magnitude of temperature difference across them is the same, they would have the same efficiency. ... 1answer 49 views ### Is there a net increase of temperature in thermal equilibrium? [closed] If I have two objects sitting side by side let's say a water pump running at 10 degrees c and a processor running at 50 degrees c. The heat transfers from the hotter to the colder object until they ... 1answer 38 views ### First and second laws of thermodynamics: getting increments from inexact differentials First law of thermodynamics states that$$\tag{1} dU=\delta Q + \delta W$$whereas second law of thermodynamics states that, for a reversible process,$$\tag{2} dS= \frac{\delta Q}{T} $$I have ... 1answer 57 views ### Energy of moving particles [closed] When particles move through a space with a certain velocity, which kinds of energy do they have? They should have translational energy because of their motion, right? But do they also have sensible ... 0answers 28 views ### What is the work energy theorem? Work energy theorem is one of the fundamental theorem in physics. Simply it is a relation between work and kinetic energy of a body. Then a question arises that what is the work energy theorem is all ... 1answer 33 views ### Is it possible to estimate the composition of a mixture between ice and liquid water from a temperature heat graph? [closed] I'm confused whether the equation for thermal equilibrium can be used to obtain the composition of a mixture with only having as information a graph. This happened when I attempted to solve a problem ... 2answers 27 views ### Validity of equipartition theorem and choice of coordinate axis While reading through the basic derivation of how kinetic energy is related to temperature, I stumbled upon equipartition theorem where \frac{1}{2}mv^2 = \frac{1}{2}kT thus \frac{3}{2}kT in 3-... 1answer 31 views ### 2nd law of thermodynamics violation? [duplicate] What if I assume an ideal gas in a cylinder having frictionless piston and perfectly insulated walls with a perfectly conducting base is kept on a reservoir at temperature T which is greater than ... 1answer 30 views ### The reversible Carnot cycle is the most efficient between T_2 and T_1. Is it a form the second law itself? The second law of thermodynamics proposed by Clausius, Kelvin, Carnot ..etc in its original form as T dS> dQ for irreversible process and Tds =dQ only for reversible thermodynamics process. This ... 2answers 44 views ### Apparent contradiction concerning the net work of a Carnot cycle The net work of a Carnot cycle, W, is$$\tag{1}W=Q_{h}-Q_c.$$This work also satisfies$$\tag{2}W=Q_{h}\bigg ( 1-\frac{T_c}{T_h} \bigg )$$Let us fix Q_{h}, the amount of heat initially ... 2answers 27 views ### Deriving Q_{1}-Q_{2}=W for a perfect gas that had gone through a Carnot cycle I saw multiple times that if an engine, say Carnot engine, absorbs heat Q_{1} at T_{1}, does work W, and expels heat Q_{2} at T_{2}, then we should have$$\tag{1}Q_{1}-Q_{2}=W.$$Let us say ... 1answer 109 views ### Thermodynamic Equilibrium math. characterisation d P=0 question I have a basical question on the mathematical condition characterizing a system beeing in thermodynamic equilibrium: Let P(A, B, C) is a thermodynamic potential with natural variables A, B, C ... 1answer 43 views ### Understanding that kelvins statement of the second law I am having a bit of trouble understanding the inequality given below: Fig 13.10(b): I am guessing that it looks as though all the heat in is going to do work, hence the violation (although I cant ... 0answers 23 views ### thermal expansion and thermodynamics (a brass plate) [closed] A bolt hole in a brass plate has a diameter of 1.200 cm at 20°C. What is the diameter of the hole when the plate is heated to 220°C? 2answers 82 views ### Why must all natural processes be irreversible? My thermodynamics lecturer was talking about reversibility and the idea of spontaneous change and he mentioned that all natural processes are irreversible. Can someone offer some sort of proof or ... 3answers 41 views ### Pressure and volume [closed] Currently, I am working on this experiment where I hit a balloon with a small object so that the pressure inside a balloon changes. The pressure increased when I hit the balloon, but I need to ... 0answers 29 views ### Work done in an irreversible adiabatic process [closed] This is a problem I encountered while solving SS Krotov. A vertical thermally insulated cylinder of volume V contains n moles of an ideal monoatomic gas under a weightless piston. A load of mass M ... 0answers 26 views ### Would a group of molecules in a container, settle down after a long time? (considering that no gravity acts on them) [duplicate] Because, every time they collide, don't they emit radiation? As in, losing energy in the form of this radiation, So eventually, won't they lose all of their kinetic energy? Of course the time taken ... 1answer 35 views ### Thermal diffusity. What do I use? [closed] I'm not a physics expert. Actually don't know much at all but I'm trying to find an answer to a problem. If I had a silicone (or clear vinyl if more appropriate) tube with .25 inch interior ... 2answers 32 views ### When to use emissivity in Stefan-Boltzmann Law? In Stefan-Boltzmann Law:$$q=σAe(T_1^4−T_2^4) I sometimes see it written with emissivity, $e$ and sometimes without. How do you know whether to include it? I know $e=1$ for an ideal radiator and ...
In Blundell's Concepts in Thermal Physics, page $117$, the author defines an adiabatic expansion as follows, The word adiathermal means ‘without flow of heat’. A system bounded by adiathermal walls ...