# Questions tagged [kinetic-theory]

Kinetic theory is part of statistical physics. DO NOT USE this tag for macroscopic kinematics; use the [kinematics] tag instead.

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### My interpretation of kinetic theory of gases predicts empirically false thermal decomposition temperature

I have an intuition that, for 50% thermal decomposition of water gas, the average collision energy must equal the $2H_2 + O_2 \iff 2H_2O$ enthalpy of reaction divided per unit molecule. I have another ...
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### How can mechanical equilibrium be guaranteed in adiabatic expansion? [closed]

Assuming I have a perfectly thermally insulated metal piston in my hand. I reach for the piston, pull on it and let go again- nothing moves. What happened to the gas in my system: T down, p down, V up....
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### Radial dependence of temperature of solar wind?

How does the temperature of the solar wind plasma depend upon radial distance from the Sun?
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### What is kinetic arrest?

I know what kinetic energy is and what chemical kinetics is, but what is kinetic arrest? Could someone please explain? There is no Wikipedia article, and googling throws up only journal articles (...
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### Why is time of contact not taken in finding rate of change of momentum in derivation of kinetic gas equation?

In derivation of kinetic gas equation, the time taken for rate of change of momentum is taken as 2l/u but the force is change of momentum divided by time of contact so why are we taking time for gas ...
1 vote
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### Why temperature increases with increase in volume?

If We heat an ideal gas, its temperature rises and it's molecule becomes energetic hence they move more and more away from equilibrium position. But when we increse the volume of gas , why does its ...
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I look to solve analytically the Vlasov-Maxwell equations for a magnetized hot plasma $$\frac{\partial f_{s1}}{\partial t}+\vec{v}\cdot\frac{\partial f_{s1}}{\partial \vec{r}}+\frac{q_s}{m_s}\Big(\vec{... 3 votes 3 answers 109 views ### How can the temperature in a column of gas be uniform, if kinetic energy increases when gas molecules go down? I cannot wrap my head around a supposed temperature gradient versus total energy gradient paradox for thermodynamic equilibrium of (open space ) gas in gravitational field. For simplicity, consider ... 1 vote 0 answers 17 views ### Physical interpretation of one-particle density, as expectation value of finding a particle with a specific momentum at a location at a time I was reading Statistical Physics of Particles by Mehran Kardar. In unit 3.3 of chapter 3 named Kinetic theory of gases, the author derived the BBGKY hierarchy. Now in the derivation, the author ... 1 vote 1 answer 33 views ### Why are total kinetic energy and interaction energy roughly the same for a liquid? Let's say one has a collection of point particles, each with a kinetic energy and (e.g. Coulomb) repulsion between all of them. Under certain conditions, the system will evolve to the stable state ... -3 votes 1 answer 38 views ### Is everything in nature a source of heat? [closed] A source of heat is something from which heat is originated or obtained, whereas heat is the energy transferred due to temperature difference so heat is relative as the temperature difference is. Thus,... 0 votes 1 answer 26 views ### Collisional cross-section from attenuation factor I am trying to find the mean free path of silver atoms travelling through air (I am given the temperature, pressure and that they are attenuated by a factor 2.72 in a distance of 10^{-2}m). I know ... 1 vote 1 answer 53 views ### Quasi-linear theory of plasma, some queries I was studying about quasi linear theory of plasma turbulene and stuck at some questions (derivations), I could able to derive upto Eq.14 of this paper, but not sure how proceed for deriving the ... 0 votes 1 answer 17 views ### Kinetic energy of evaporated gas as source of energy loss for evaporating liquid? Currently, I am looking at a system that is composed of a metal cylinder (lets say Iron) that is being heated by a laser inside of a vacuum chamber. As the laser strikes the surface of the iron, part ... 3 votes 1 answer 177 views ### Significance of Stokes Hypothesis When we derive the Navier-Stokes Equation, we come across a a common assumption made by Stokes that makes the two quantities namely Mechanical pressure and Thermodynamic pressure equal to each other. ... 0 votes 0 answers 28 views ### Pressure exerted by a single electron in an spherical bubble This is from APhO 2010, Problem 3, Part (A) When an electron is planted inside liquid helium, it can repel atoms of liquid helium and form what is called an electron bubble. The bubble contains ... 0 votes 0 answers 15 views ### Why does rotational collision number in dilute gases such as N2 increases with temperature? In the kinetic theory of dilute gases, the rotational collision number and rotational relaxation time are defined as follows- rotational relaxation time = time required for the establishment of ... 2 votes 1 answer 58 views ### Velocity distribution function and Boltzmann factor In Blundell and Blundell's Thermal physics book there is a chapter on the explanation of the Boltzmann distribution. It is explained that for canonical ensemble with a reservoir at temperature T in ... 1 vote 0 answers 112 views ### Ratio of mean free paths between two equal volumes at different temperature, separated by a partition with pinhole Question: A container is divided into two equal parts I and II by a partition with a small hole of diameter d. The two partitions are filled with same ideal gas, but held at temperatures T_I​= ... 1 vote 0 answers 42 views ### Time Scales in the BBGKY Hierarchy (I am following Chapter 3 of Mehran Kardar's Statistical Mechanics of Particles)When working with the BBGKY hierarchy of equations, we get the following for the two-particle probability density f_2: ... 1 vote 1 answer 53 views ### Why air particles in a longitudinal sound wave don't leave their mean position? Air particles have random zigzag motion. However,in a longitudinal sound wave in air the particles vibrate to and fro about their mean position in the direction of propagation of sound wave(ie, the ... 0 votes 0 answers 43 views ### Doubt on obtaining Boltzmann Equation given in the book "Modern Cosmology" Ed 1, Dodelson, equation 3.9 My question refers to Equation (3.9) of Dodelson "Modern Cosmology" Edition 1,$$ n^{-3} \frac{d(n_1 a^3)}{dt}=n_1^0 n_2^0 <\sigma v>\{\frac{n_3 n_4}{n_3^0 n_4^0}-\frac{n_1 n_2}{n_1^0 ...
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I think most gases are light but Radon is really heavy. I of course know that plenty of gases are not radioactive, but could the reason that Radon is a gas be due to the radiation contributing to the ...
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### Is is possible to extract an effective Hamiltonian from a Boltzmann equation (or any other kinetic theories)?

I got kind of confused when reading Xiaogang Wen's famous textbook Quantum Field Theory of Many-body Systems. In Section 5.3.3 the book claims that From a kinetic theory of Fermi liquid (a Boltzmann ...
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### Resultant particle distribution function for mixing of two particle species

I would like to know if there is any way to compute the resultant particle distribution for system where two kinds of particles are mixed. For me one kind is Maxwellian and another is non-thermal ...
1 vote
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### At freezing/condensation point, why does the temperature remain constant? [duplicate]

I understand that at freezing and condensation points, potential energy of molecules are given off to form intermolecular bonds while the kinetic energy of the molecule stays constant. My question is, ...