Kinetic theory is part of statistical physics. DO NOT USE THIS TAG for macroscopic kinematics. In this case, use the tag [tag:kinematics] instead.

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Momentum change in collisions (Drude model)

A particle suffers elastic collisions with scattering centers with a probability of collision per unit time $\lambda$. After a collision the particle is in a direction caracterized by a solid angle ...
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Why does the temperature of a gas inside a moving container not increase with velocity?

A rectangular (simplified) container with rigid surfaces, has a certain mass of ideal gas within it, and it accelerates in free space, undergoing rectilinear motion. There are no dissipative ...
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Kinetic Energy of a system of ideal gas

For a nuclear fusion reaction in which goes as follows: $${}^2_1H + {}^1_1p \to {} ^3_2He + \gamma$$ If we assume that the mixture of deuterium nuclei and protons behave as an ideal gas, then can ...
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Partial pressures - beyond the concept of point masses

Imagine that I have 100 atoms of oxygen and 100 atoms of lead put together in a container. By kinetic theory of gases, they should be considered as point masses thus the partial pressure of oxygen ...
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Extreme temperatures, relativity and kinetic theory

According to kinetic theory, average kinetic energy is proportional to temperature. Supposing $k_BT/2$ per particle, can we use relativity and kinetic theory to calculate, e.g., the temperature and ...
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111 views

Flow rate of gas down a pipe at low pressures

I'm trying to understand an 'approximate derivation' of the flow rate of gas down a pipe at low pressure from my book (an example problem). It uses the result that the flux of a gas is given by ...
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Randomness of submolecular phenomena

Why do models of submolecular phenomena involving randomness work? Do these phenomena appear random to other submolecular particles? For example, people can use Einstein-Smoluchowski to characterize ...
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42 views

Is it possible to describe the geometric mean of the Maxwell-Boltzmann distribution?

This may be a more appropriate question for the Mathematics stack exchange, if so forgive its extraneousness. We know the expected value of the distribution, analogous to the weighted arithmetic mean ...
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Error in mathematics of collision theory

I'm making lecture notes, and I felt that it would be important to explain some of the math behind collision theory. I come up with a problem, however. Here, I'm trying to show that the collision of ...
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Cauchy Problem for Boltzmann Equations

One of the first profound analysis about the solutions of the Boltzmann Equation was given by DiPerna and Lions in the late 1980s. You can find one of their main papers here: ...
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Mean free path in spherical coordinate

I am thinking about a distribution with spatially inhomogeneous cross section in spherical coordinate. Starting with 1-dimensional case, a change of the flux passing through a slab with length $dx$ is ...
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99 views

How to formally write down the Boltzmann equation?

Can someone write down the Boltzmann equation, not neglecting any of the variables of the involved functions and integrals? Specifically, how to concisely capture the "primed" variables in a sensible ...
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Confined in a box, what is the average distance between a particle hitting a side?

This particle, alone in the box, at a constant velocity $v$, travels in straight lines until hitting a side of the hollow cube, bouncing off in a random direction independent of incident angle (I know ...
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How to derive entropy transport equation from heat equation?

Suppose I have heat equation: $$ \rho (\partial_{t} + (u \cdot \nabla)) T = -\nabla \cdot \mathbf R, $$ where $\mathbf R$ - some vector and $T$ - temperature. How to get the equation for entropy $S$ ...
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What does the temperature of the early universe tell me?

I am re-reading Weinberg's book "The First Three Minutes". In the Introduction he makes this statement: "At about one-hundreth of a second, the earliest time about which we can speak with any ...
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Applying Statistical Mechanics to Formulate Corrosion (Rusting)

I wanted to try and take my current knowledge of statistical mechanics (first quarter undergraduate course completed, beginning researcher in far from equilibrium statistical mechanics, basic ...
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55 views

Recombination time for ionized atoms in a low pressure gas?

I am looking into some new physics and had the following question come up: You have a neutral gas of let's say, CO atoms at 1 nanoTorr. An electron(s) comes passing through the gas ionizing only 1% ...
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Effusion of particles from one box to another - pressure calculation

Suppose we have a container divided into equal halves. Right half is fixed at temperature $T$, volume $\frac{V}{2}$. Initially it has pressure $P_0$, a hole of area $A$ is opened between them. I ...
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Height of a piston in a heated cylinder containing H2O

I'm a first time user and I hope I won't be too enigmatic asking the following question: I have a cylinder (radius= $6$ $\text{cm}$) with a frictionless piston on top of it and inside $30$ $g$ of ...
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230 views

Simple: What do these ballistic impact numbers represent?

I bought physics for game programmers, found here, today to study ballistic impact, but I'm confused as to where a few numbers are coming from. I'm basically looking to understand what the values ...
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pascals law of liquids in terms of kinetic theory of molecules

Suppose a cylindrical container of base area A filled with water is carrying a piston on top. If the piston applies no force on the liquid, assume the pressure is P for a point located on the boundary ...
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124 views

Average kinetic energy of molecules hitting a surface

I am trying to prove that the average kinetic energy of gas molecules hitting a containers surface is $2k_{B}T$ instead of the average for the entire gas, which is $\frac{3}{2}k_{B}T$, where $k_{B}$ ...
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What is isotropy actually & how does it ensure that exactly same number of molecules will move in either sides?

Kinetic theory is also an example of isotropy. It is assumed that the molecules move in random directions and as a consequence, there is an equal probability of a molecule moving in any ...
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Dependence of kinetic friction on relative velocity

While I was reading my book I came across a line that tells that there is slight dependence of kinetic friction on velocity of relative motion of the bodies. Can anyone tell me how is this so?
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How does one determine the breakdown voltage of a solid-in-liquid suspension?

So I'm doing a project in which we are supposed to collect micro-scale conducting metal particles from a suspension of it in water (which is deionized). Suppose that I am charging the particles ...
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33 views

Degrees of freedom of particles in Lattice Boltzmann method

Is it true that in Lattice Boltzmann method particles have only one degree of freedom even in 3D case? Can someone explain that fact or provide a link? Thanks!
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How close together must air molecules be to bounce off one another?

When, say $\text{N}_2$, is in the wild, it regularly collides with other $\text{N}_2$. I assume these collisions happen as, having become sufficiently close, the atomic electrons are repelled from ...
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How does the volume change affect an adiabatic process?

A gas consisting of rigid diatomic molecules was initially under standard conditions. Then the gas was compressed adiabatically, 5 times the original volume. Find the mean KE of rotating molecules ...