Questions tagged [thermodynamics]
Covers the study of (primarily homogeneous) macroscopic systems from a heat/energy/entropy point of view. Consider also using the tag: [statistical-mechanics].
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Work done by a gas on a piston
Work done by system on the piston should be F(sys)•(ds) and Work done by the surrounding on the piston should be F(sur)•(-ds) thus the net Work is stored in the piston as its kinetic energy . The ...
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Does galactic evolution approximate the distribution of the prime numbers due to the 2nd law?
So, this question occurred to me after watching these two videos in quick succession and then doing some additional lit search, I apologize if my terminology is imprecise/inaccurate since this isn't ...
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Mass of ice block needed to cool area
I intend to grow king oyster mushrooms inside a small greenhouse tent. The problem is the mushrooms prefer a temperature of approximately 60F. I'm trying to avoid needing to run an air conditioner to ...
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Equation of a heater heating a room temperature [closed]
I am trying to model how the room temperature depends on the temperature of the heater in the room. I have collected the data on these parameters: let's say at time $t$ there is $T_r(t)$ – room ...
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Work of a thermodynamic cycle involving steam [closed]
Today, I had a thermodynamics test which had a really difficult question on thermodynamic cycle involving steam. I'm a chemical engineering student so this question involves data tables such as ...
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How does warmer air temperature cause droughts? [closed]
I recently watched a video report of wine farmers in the south of france losing large amounts of their plants due to extreme droughts. It was made very obvious that the people filming the report think ...
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Can adding more energy cause the temperature to drop again?
In a system, the total energy is composed of Electronic >> Vibrational > Rotational >> Translational.
As far as I understand, temperature is only related to the average kinetic energy, ...
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Tilloston Equation of State to determine the temperature
Given a hyper-velocity impact and the Tilloston Equation of State (Sec. 2.1), how do I determine the temperature? I suppose we use the internal energy E to find the temperature for a given EOS, but I ...
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Estimating the cooling of a small piece of metal [closed]
Suppose I have a small piece of aluminum 6061-T6 alloy. Is it possible to estimate how much the metal's temperature would decrease from 100 degrees Celsius in 2 seconds?
Assuming,
The room temperature ...
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Thermal motion at higher pressures at constant temperature
I would like to know if the thermal motion of molecules stays constant if the pressure is increased at constant temperature or not. The viscosity increases with pressure, thus the friction between the ...
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Similarity between holonomic/nonholonomic constraints and state/path variables in thermodynamics
I have recently learned about holonomic and nonholonomic constraints in analytical mechanics, and how they can be expressed as exact (Pfaffian form); for example:
$${\displaystyle df_{i}=\sum _{j}\ A_{...
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Relationship between volume and temperature of an ideal gas
I am self-studying thermodynamics, and was reading up Carnot heat engine (Yunus Cengel - thermodynamics book). So, the experiment in the textbook is set up such that, we have an adiabatic piston-...
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Callen Thermodynamics and an introduction to thermostatics problem 3.8.1 [closed]
In Callen Thermodynamics and an introduction to thermostatics is given the fundamental equation for a simple paramagnetic sistem:
I'm stuck in the problem 3.8.1 that is
I looked in the solution ...
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Proving entropy is an exact differential [duplicate]
I have been trying to understand something that my professor explained and I have tried everything (books, my classmates' notes, internet) but I can't understand, can you please help retrieve the ...
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What differs temperature from the mean kinetic energy of a particle? [closed]
The mean kinetic energy of a particle for an ideal gas is related to temperature by:
$$ KE = \frac{3}{2} k T \tag{1} $$
My question is why $KE \neq T$. To me it seems a far simpler relationship if ...
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Are source and sink part of system or are they part of the surroundings?
This question is regarding the interactions of a thermodynamic system with its environment: do we count the sources and sinks of entropy (heat) as part of the thermodynamic system or as part of the ...
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Definitions of Thermodynamics and Holography
There are many differences between the laws of thermodynamics and the laws of black hole thermodynamics (BHT):
Zeroth Law: In thermodynamics, the Zeroth Law establishes the notion of thermal ...
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Probability and Thermodynamics: Analysing feasibility of 50 benches problem
Question:
I have a thought experiment that involves dropping 50 benches from a height through an open roof and examining the probability of them spontaneously arranging themselves into neat rows and ...
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Work done by adiabatic expansion derivation
I know that $W=-C_v(T_2-T_1)$ for an adiabatic expansion, and I know how to derive it. However, in this video (https://youtu.be/gaZmZjBtgAM?si=Px3v2qDG3CIdupgi&t=358) it mentions the formula $W=-\...
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Temperature Estimation for Insulated Bottom Surface in Water Cooling
In a 2D plane heat flux q'' is incident on an insulation layer (which has a thickness L and a thermal conductivity k). The bottom surface of this insulation layer is exposed to water cooling with a ...
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Will hot object near ceiling vent create more draft? [closed]
As in the picture, we have a room with vents at the bottom to let cold air in and at the top to let hot air out. Normally the air flow is limited by the temperature gradient (correct me if I'm wrong). ...
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Speed Limit to Quantum Computing [closed]
The speed of a real-world reversible computer scales linearly with applied force and entropy. To prove this, I will use $N$ as the number of steps (physical operations), $h$ as Planck’s constant, $k$ ...
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Interpretations of Enthalpy [closed]
Enthalpy - unlike various other thermodynamic quantities like the internal energy $U$, what I will term the mechanical potential $PV$ and entropic energy $TS$ - seems rather difficult to interpret. I ...
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Empirical equivalence of shifted chemical potential $\mu_i$
It is often said that, in classical thermodynamics, entropy $S$ and energy $U$ are defined only up to an additive constant proportional to the total amount of substance $N=\sum_i N_i$ (where the sum ...
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Heat and harmonic oscillators [closed]
I admit this is a bit of 'spielerei', but I find it mildly intriguing nonetheless.
So, consider the internal energy of a system $U(x_0)$ where $x_0$ is say the centre of mass coordinate at time $0$, ...
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Verification of the second law of thermodynamics for liquids?
I have a pure math background and I am currently self-learning physics.
To mathematically justify and understand the Second Law of Thermodynamics, mathematicians and physicists have studied the motion ...
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What does heat do to atoms? [closed]
If infrared energy is absorbed as velocity and not a force, is it the electron spin that is absorbing as seen by frequency? How does it work for increased velocity, could it work to decrease velocity ...
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What is the number density of CMB at higher temperature? [closed]
What was the approximate number density of CMB photons when the CMB had a higher temperature of 897 K? (Hint: You can assume that photons in a thermal distribution have a mean energy of 3kT). Answer ...
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Thermodynamic limit as zero-mass limit
Given a gas of $N$ particles, with mass $m_i$ of $i$th particle, in a volume $V$, usually the thermodynamic limit is achieved by sending $N, V \to + \infty$ while keeping fixed thier ratio $\frac{N}{V}...
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Properties of a Burning Candle
I was just having a discussion with some friends about candles, and I came up with a good question: do candles burn at a constant rate?
I would assume that the answer is no, as the bigger the candle, ...
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How to calculate air changes required per hour to offset heat inputs (watts) per hour? [closed]
Ive got a cupboard which is 1m wide, 1m deep, 2.4m high. So 2.4m3 in total.
There is equipment in the cupboard that outputs 500w of heat per hour.
I want to keep the cupboard at the ambient temprature ...
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Investigating the Effects of Explosive Boiling on Metals [closed]
I am currently engaged in academic research aimed at understanding the potential effects of explosive boiling on metals. While there is a substantial body of research on the factors influencing ...
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Using the electrolysis of water to cool a room [closed]
Browsing the internet today I came across this very esoteric paper which purports to describe the construction of a device which uses the electrolysis of water into hydrogen and oxygen (a highly ...
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Stochastic thermodynamical entropy production on growing state space
Suppose we have a stochastic process for a biased random walker starting at a position $x_0 = 0$. At a discrete time $n$, it can either move a distance $s^n$ to the right with probability $p$ or a ...
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Vapour mass to remove from tank in VLE to reduce a certain amount of pressure [closed]
I have a tanktrailer and a tank containing a cryogenic VL-mixture of methane. I would like to calculate how much kg of Boil-Off gas I would need to take out from the tank to the trailer in order to ...
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How do cold/hot atoms move faster or slower than their thermal energy suggests?
I have been frequently stuck on this question since first realizing it in the shower. While watching the hot water drop from the above shower head, and then watching cold water drop, I realize they ...
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How to calculate habitable zone for Exoplanets? [closed]
I have a question about the habitable zone of stars for exoplanets, which arises from the fact that the "habitable zone" is essentially a myth, as you can tell from Earth, which, without the ...
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Monotonic functions (Problem on intensive properties) [closed]
I was trying to solve a problem on intensive properties. I couldn't solve it. I am attaching the question and my attempt to solve the problem below. Can someone please help in finishing the problem?
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How to solve part b of the problem? (thermodynamics) [closed]
How to solve the part(b) since number of moles of gas is changing. It is going from system A to B. n $Cv dt = pdv$. We can apply this equation to system A only if the number of moles are not changing.
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Why do we expect unitarity to be preserved in the black hole information paradox?
Consider the following way of describing the black hole information paradox:
Suppose we start with a pure quantum state and a black hole of mass $M$. Now we throw the pure state into the black hole ...
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Thermodynamics: A piston can freely move inside a horizontal cylinder which is closed from both ends
Is it safe to say that regardless of where the piston is, the final pressure on each side of it would remain the same. And if yes, then why?
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Joules experiment: how to find the final temperature of the second compartment given just the initial and final temperature of first compartment [closed]
I have this problem I am trying to solve where we have a set up very similar to the one in Joule's experiment where he proved that the internal energy of an ideal gas depends only on its temperature. ...
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The action of anti-bumping granules
Anti-bumping granules are usually small stones. I presume that the principle of these granules ensuring smooth boiling, is that it blocks the upward motion of solution molecules.
Usually the stones ...
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Equation-of-state for a photon gas
What is the equation-of-state for the photon gas ?
Remarks:
Here Photon gas = Black body radiation. For more background see How does radiation become black-body radiation?, Does thermal energy ...
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Light, Work, and the 2nd Law
I am trying to figure out what restrictions there are on converting light energy into work.
I understand that solar energy can be converted to electrical energy with roughly 90% Carnot efficiency. ...
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Entropy and Dissipation
I've grown accustomed to thinking of entropy as something that reduces the amount of mechanical work a system can produce. However, this does not seem to be reflected in the mathematics.
For example, ...
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Why are my ice cubes sticking in their containers?
I make my ice in those little round to-go containers that usually hold sauces/dressings.
When using the clear containers, the ice sticks to it and requires heat or violence to get it out. When I use ...
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Contradiction in Thermodynamic Work and Mechanical work [duplicate]
The first law states that $ \Delta U = Q - W $ where W is the work the system does on the outside. If there is no heat added, the change in energy is equal to the work done. If the work is negative, i....
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Position-based thermal states in a quantum optical experiment
In a quantum optical experiment, suppose there is an initial source $S$ at a plane $P\subset \mathbb R^2$ emitting radiation in a specific state. In order to describe such state in the position basis, ...
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Partition function of particles having magnetic moment $\mu$ placed in a magnetic field $B$. (Particles obey Maxwell-Boltzmann statistics.)
How to calculate partition function in this case? Like, here we get two discrete energy levels $uB$ and $-uB$ but particles obey MB statistics. So we can't use integration formula of partition ...
