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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If our planet had more gravitational force would rain clouds still form? If so, would they form at the same elevation, higher or lower?

If the acceleration of gravity on earth were greater would rain clouds still form? If so, would they form at a lower, higher or the same elevation? My question actually is related to a curiosity about ...
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Is it possible to define concepts like free energy in the diffusion process?

How does the idea of free energy (which we derive from the canonical partition function) fit in the domain of non-equilibrium processes like diffusion?
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How statistical thermodynamics actually solves these problems?

Our primary objective in thermodynamics is to explain the bulk behavior of matter. In trying to do so we may think of going with the straightforward approach of explaining the bulk behavior by ...
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When the temperature increases to four times the starting temperature, how are the equations for $\overline Z$ and $\overline \lambda$ affected?

A certain amount of ideal gas is stored in a container of fixed volume, the initial temperature is $T_0$, the average velocity $\overline v_0$, and the average collision frequency $\overline Z_0$. If ...
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How can I safely heat up a AAA battery? [duplicate]

I’m working on a science experiment in whether or not the temperature of a battery affects how long it will last. It’s the middle of winter where I am and I’m not quite sure how to safely heat up the ...
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Thermodynamics entropy physics [closed]

At 1C temperature, for ice to change in liquid the change in entropy for system is less negative, then the change in entropy for sorrounding which is more positive, so why is that? Although the bond ...
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Maxwell distribution solely using the Stosszahlansatz and geometric transformations?

Background To quote Wikipedia: The assumption of molecular chaos is the key ingredient that allows proceeding from the BBGKY hierarchy to Boltzmann's equation, by reducing the 2-particle distribution ...
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Heat Transfer by convection questions [closed]

It's been a decade since I last used heat and mass transfer concepts and I am struggling to find the answer to my question and thought I could find some help here. I am interested in studying the ...
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Are there things with different physical attributes that serve exact same purpose in a system? [closed]

I’ve been puzzling about this cross-disciplinary concept for the last week. Can you think of any two things that have different physical make up that serve the exact same purpose? For instance, ...
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Can we say that there exists an upper bound to which heat dissipation can be minimized in pulling the plates apart of an ideal capacitor reversibly? [closed]

So I thought like this, As we know, $$dw = du + dq.$$ Now, internal energy is change in microscopic potential energy and kinetic energy Assuming, all change in internal energy to be change in electric ...
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Does isothermal expansion not beat the efficiency of Carnot Heat Engine?

Ques: If I just take the 1st step of a Carnot Heat Engine (CHE) than it turns out to be more efficient than the CHE itself. Explanation: The 1st step of a CHE is the pure isothermal expansion of (...
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General solution of wave equation in homogenous, isotropic, linear, source-free material

Starting with Maxwell's equations we have $$ \nabla \times \vec{E} = - \partial_t \vec{B}$$ $$ \nabla \times \vec{H} = \vec{J} + \partial_t \vec{D}$$ $$ \nabla \cdot \vec{D} = \rho$$ $$ \nabla \cdot \...
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Is the heat add at constant static pressure or constant total pressure in an (ideal) jet engine combustor?

The Brayton cycle involves a constant pressure heat addition process(loss less combustor). So, in a jet engine combustor, does the total pressure at the exit of the combustor (Po4) remain equal to the ...
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Isn't energy absolute according to Thermodynamics?

I was taught that Internal Energy $U$ is a relative quantity: only changes in $U$ are meaningful. It doesn't have an absolute value, since it always comes with an arbitrary constant (for example $U = ...
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Entropy change during adiabatic expansion of ideal gas

I was told that the entropy change is $0$ during adiabatic expansion. However, according to $\mathrm dS=\frac{C}{T}\,\mathrm dT$, $\delta S$ is not zero because temperature is not constant during ...
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Vapor Compression Refrigeration Cycle

My question here is, why do we need point 2 to be on the saturated liquid line, i.e. why do we need a saturated liquid for the throttling process? Why can we not use it in the liquid region or ...
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Maximum Efficiency of Thermodynamic Cycle [closed]

I am a non-engineering student about to start an MSc on Sustainable Energy and I'm trying to get a head start so I don't fall behind. I would really appreciate some guidance on the following past ...
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Is metaphysics a subject that should replace physics and philosophy? [closed]

I'm really seeking some insight and the following may seem opinionated, but it's really my observations and I could be wrong and I'm completely open to hear thoughts and correction from anyone. If ...
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Free energy minimization, statistical vs thermodynamic

When we speak about minimization of free energy there are two approaches, one from statistical physics and one from thermodynamics: Statistical physics tells that is we consider a system in thermal ...
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What is the meaning of a thermal equilibrium between matter and radiation?

I understand that the thermal equilibrium between two bodies means that the two bodies attain the Same temperature. Therefore,there is no flow of a thermal energy between them. However, I don't know ...
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Are there any chemical reactions which result in the density of a water decreasing?

I'm not a chemist or a physicist, I'm not even college educated, so forgive me if I use the wrong terminology or do not understand the question I am asking. I understand that dissolving salt into ...
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Partial pressure problem

Recently while reading the literature that ethyl alcohol has a higher partial pressure than water, thereby having a tendency to evaporate and be lost.' My understanding is that the higher the partial ...
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What does the no-hair theorem state about the entropy of black holes?

So does the no hair theorem say that all classical black holes will have zero entropy? If yes, why?
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Problem in code for Monte Carlo method for frustrated Ising model

I'm studying Monte Carlo method (it's related to my school project). The code I'm using I got from a paper by Jacques Kotze (https://arxiv.org/abs/0803.0217). In his paper, he uses the Monte Carlo ...
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Spring compressed by external constant force,pot.energy stored over it is half of the work done by force, where does half gone [duplicate]

I have a doubt that for an ideal (massless)spring if apply an constant force over it until equilibrium the energy stored over it is ( kx^2)/2 and the work done by force is kx^2 so where the half of ...
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Boltzmann or Gibbs entropy for the canonical ensemble?

For the microcanonical ensemble the entropy, is given by the Boltzmann entropy which equals: $$S = k_\mathrm{B} \ln(\Omega(E))$$ where $k_\mathrm{B}$ is Boltzmann's constant and $\Omega(E)$ the number ...
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What is the difference between Root means square speed and average speed [closed]

!see the above image]1 I am using Average speed of gas molecule to find out avg Kinetic energy What is the difference between between finding out the kinetic energy by Root means square speed and ...
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Boiling point of hydrogen: relation between pressure and temperature near of triple point

The phase diagram of hydrogen suggests that near of the triple point the relation between pressure and temperature at the boiling point is given by $$P = P_0 + (T - T_0)^\alpha,$$ with $(P_0,T_0) =$ (...
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Boltzmann distribution and probability of finding the system with specific energy

For sake of simplicity assume classical discrete systems. If we have a system ($\text{S}$) coupled to a reservoir ($\text{R}$), then a microstate of the combined (isolated with fixed energy $E$) ...
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Is using platinum as a heating element 10x less efficient than using nichrome? [closed]

I notice that platinum has about ten times less resistivity than nichrome. Does that imply platinum requires 10x as much electricity as nichrome to produce the same amount of heat when used as a ...
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Why does snow disappear without melting?

During very cold weather, snow often gradually disappear without melting.
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How does one show that $\beta$ is the same for different substances in thermal equilibrium?

In the section regarding quantum statistical mechanics, Griffiths uses the method of Lagrange multipliers to calculate the most probable energy configuration $(N_1,N_2,\dots)$, where $Q(N_1,N_2,\dots)$...
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What is the thermodynamic spin-vector distribution?

Background So my understanding is the Fermi-Dirac distribution tells us about the probability of a particular energy state for spinors. Also, from Spinors and Space-Time Volume $1$ - Penrose and ...
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Can an actual physical system have zero entropy? [duplicate]

Obviously, a pure quantum state has zero entropy. It appears that in theory, this is correct; but in practice, it is not, because there is always some mixing with the environment. So, zero entropy is ...
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Calculating the internal energy

I would like to know how to calculate the "internal energy" of an object. What I mean by internal energy is something like this: 2kg of carbon has a higher "internal energy" than ...
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How can $dQ=nC_mdT$ be used in various thermodynamic proofs?

I have seen the equation $dQ=nC_mdT$ for ideal gases often used in certain proofs in thermodynamics(such as $C_m$ for polytopric process). However, I feel this expression is wrong as a general ...
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How can we define a "free energy" for a protein configuration?

In my naive understanding, a free energy (either Gibbs $G$ or Helmholtz free enrgy $F$) is a property defined for an ensemble of microstates under certrain circumstances. (NPT or NVT) But I often see ...
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Net efficiency of carnot engines operating in series [closed]

Two Carnot engines are operated in series. The first one between temperatures T1 and T2 (T1>T2) and the second engine between T2 and T3 (T2>T3). Assume that the second engine absorbs all heat ...
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Can a mass on a spring oscillate when it is in contact with a heat bath?

I am reading statistical mechanics from Concepts in Thermal Physics, the author states the following after deriving the equipartition theorem. A mass on a spring has energy $E$ which is given as the ...
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Which effect in everyday life is due to the Boltzmann constant? [closed]

The question says it all. How can I best convince a non-physicist that the Boltzmann constant describes the world around us? Are there any striking effects around us that are due directly to the ...
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What are some examples of microscopic quantities?

Mass, volume, energy, entropy, temperature, pressure are some macroscopic quantities. Which means we can think of them even without considering the molecular nature of matter. What are some examples ...
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Would isotopes of hydrogen separate in liquid phase?

According to https://www.aqua-calc.com/calculate/volume-to-weight the difference in density of deuterium/hydrogen in liquid state is 70miligrams/cm^3 vs 169miligrams/cm^3. Would this be a sufficient ...
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Query about average velocity of gas molecule

When we can say that gas molecule average velocity is 0 and in which case it is not possible?
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Do irreversible thermodynamic processes CONSTITUTE time or do they MOVE IN time? [closed]

Time can be associated with irreversibility. A broken egg can't reassemble. Most, if not all, processes are irreversible and this is associated with time going in one direction. Ŕemarkably, living ...
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Doubt regarding movement of molecules on supply of heat

When we supply heat, molecules move away from each other. When I searched on google for why this happens (https://byjus.com/question-answer/how-does-heat-energy-help-particles-overcome-forces-of-...
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Is the pressure always the same for each phase of a two-phase system?

I am currently reading a textbook called Engineering and Chemical Thermodynamics but I am stuck in one part about the State Postulate and the Gibbs Phase Rule. The Gibbs Phase rule says that the ...
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Does a water heater consume more energy if constantly kept on than if it is made to heat the water on demand?

Suppose I have a water heater, an insulated tank of water that when turned on heats water to a predefined higher than ambient temperature and keeps it at that temperature. Suppose I don't need the ...
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Speed of sound in a gas (for adiabatic perturbations in cosmology)

In the book "Introduction to Cosmology" by Barbara Ryden, equation 4.57 gives the sound speed for adiabatic perturbations in a gas with pressure P and energy density $\epsilon$. The equation ...
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Why is it difficult to make the Juttner distribution account for anisotropies?

Wiki states While the classic Maxwell-Juttner distribution generalizes for the case of special relativity, it fails to consider the anisotropic description. What are the challenges when one tries to ...
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Adiabatic expansion and phase transition paradox

It is possible for a (real) gas to increase its temperature during adiabatic expansion and whether this happens it is strongly dependent on the intermolecular interactions of the gas. We can explain ...
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