Gas Definition and 1000 Threads

We start with hydrostatic equilibrium: $$ \frac{dP(r)}{dr} = K \gamma \rho ^ {\gamma -1} \dfrac {d \rho}{dr} =-\frac{GM(r)\rho(r)}{r^2}$$ $$ K \gamma \rho ^ {\gamma -1} \dfrac {d \rho}{dr} = - \dfrac {G \rho (r) }{r^2} \int 4 \pi r^2 \rho (r) \, dr$$ $$ r^2 K \gamma \rho ^ {\gamma -2}...

I want to make a 2D game with gas (stardust) simulation. (I'm lazy to learn statistical physics and integrate thing by my self so) I want to know how gas spread, and how gas interact with circle object. There will be 2D square grid. Each cell contains values of the state of the gas (a struct...

I came across this problem while studying for my PE exam: I'm not sure what "P_r2" is supposed to represent. Obviously 480 psia is not 697.5 times atmospheric pressure. This is what the table looks like with the "relative pressure" column: How does "relative pressure" relate to the...

I have a not-so-well based intuition about this one, I think that in general odors travel farther in winter than in summer. I can smell the close-by bakery more intensively when is cold than when is hot. This might be a variety of reasons (like there being more smells to sense in summer) but I...

Method 1 is the standard and (probably) the correct answer. I was fiddling around with it and don't understand why I get a different answer using method 2. If the gas is changing pressure, then it is changing volume. So why can't I sum up the entropy changes using method 2? Using method 2 with...

Hello, I have a question regarding the ideal gas and the average free movement of a single molecule. For simplicity, let's consider a model where we have only one atom moving, and we assume all atoms have the same radius. First, we calculate the cross-section σ using the formula σ=d², where d...

This is chemistry but it's basically physics :D. I used PV = nRT, I get V = 37.44 L. This is fine. So then I have W = P(Vfinal - Vinitial). Vinitial is zero, because there was no hydrogen gas initially. So I get 3.78 kJ. And as the gas expanded from 0 L to 37.44 L, the gas has done positive...

If the surface is heated, air above it will also heat, its temperature will rise. It will cause two processes: while temperature of gas rise, its pressure will also increase, but, also, as the air molecules get more energy, they will go higher from the earh surface, concentartion of the...

It is known that while the electric current flows along the wire the energy propagates through the field near that wire (and not by means of electron gas kinetic energy) and the electrons' velocity is equal approximately to 10^[-3] m/s. Meanwhile, the electrons' velocity during the gas...

Firstly I figure out that there is a point where the temperature of the gas is the hottest and beyond that no more amount of heat is necessary, descibed as following inequation:

Dear community, I have a question comparable to https://www.physicsforums.com/threads/calculating-the-mass-of-air-in-a-pressurised-air-tank.1053707/, but with some additional peculiarities. My setup is: 1) I got a time series of gas pressure and temperature, with a time step of 2 minutes 2) I...

Hi Physics Forum Folks! What an amazing resource of knowledge, ... thanks! The question is on the attached graphic, as its much more clear with an illustration. (Please read questions on this graphics first before looking at the video below,) This video is a very quick look at the actual...

I have found the answers for T = 848.615K, P = 126137.7705 Pa and change in S = -184.27008 J/K. But my answer for work is not correct and I am not sure where I am making an error. Could someone please help me out with how to calculate work? My steps for work is : We are given: Pi = 101325 Pa Pf...

If neon is stored at 40 psi . 65 degrees fahrenheit. How do i calculate the psi in a closed system when the container is heated.

Source: Shankar Yale OCW physics I have three questions here: 1. K_avg is 3/2kT, sure. But isn't this the kinetic energy of one particle only? So why isn't the answer multiplied by avogadro's number (because one mole). 2. When doing the "typical velocity" derivation, I noticed that they used...

At first I thought these values should be equal because I thought thermodynamic work is simply the work done as the gas compresses or expands. That is, the work done as the gas expands ( and the mass gets lifted up) should be equal to the work done against gravity as the mass goes up, and the...

Need help solving this question. Can't seem to get the right answer using PV/T=constant P1V1/T1 = P2V2/T2 Patm = 75.23cmHg T1+20+273=293K STP: P=1.01 x 10^5 N/m^2 Pabs=41cmOil P1 = density x g x h = (810 kg/m^3)(9.8 m/s^2)(75.23-41)x10^-2 mOil=2717.18 N/m^2...

The notes my lecturer has provided state that the maximum temperature can be found taking p = 0 in the inversion curve formula, given as: I’m not sure how to obtain this?? These are the formulas: This is my attempt at a solution : Not sure if this approach is right?

Can someone explain to me what I am doing wrong? Trying to calculate the Temperature T using this formula I am trying to find T using most probable speed of atoms formula. T = (V^2) m/( 2k) I am getting riduculous T like 20x10^27. Why? If number of atoms N= 2x10^24 how do i get mass m? each...

Gas flow rate: 20lpm Gas: 10% ozone Injected into water Water flow rate: 120GPM Mazzei Injector: 784

After 40 years I finally got a snowblower and wow does it pump out the fumes. Pretty sure I got a high and a headache. Any tips for dealing with this? Anyone wear a vapor mask?

Let us say that the glass isn't whole under the water. If the height of the air layer under the water is ##\Delta x##, then the pressure the water acts on the gas is ##p=p_{\mathrm {atm}}+\Delta x \rho g##. But my confusion is why the "hydrostaic pressure" is ##\Delta x \rho g##, not ##L\rho...

The problem is from the book "The Principles of Thermodynamics" by ND Hari dass. It looks trivial problem, but I am not able to form logical arguements for going into next step. For example, It seems like first gas has equation of state ##PV =nRT## and second has ## \left( P_2 +\frac{a}{V_2^2}...

Verlet Algorithm with periodic conditions

I suppose that the temperature is the same for the helium as well as for the air. So ##\frac 43 \pi r^3 \rho g >m_{He}g+4\pi r^2 \sigma g##. I would determine the density of air from ##p_0 \mathrm d V=\frac{\rho \mathrm d V}{M_a}RT##. So ##m_{He}<4\pi r^2\left(\frac{p_0M_a r}{3RT}-\sigma...

If a gas flowing through a tube would meet two orifices with different diameters in the same cross section, how much of the gas would flow through each orifice and what would the gas velocity be in dependence of orifice diameter?

Hi ! To me it seems linda cycle can not liquidize nitrogen. Please explain me, can it liquidize N2? Here is how I come to this result: Imagine compressor take nitrogen 1bar 300k and gives 200bar hot, but cooled to 200bar 315k. Next n2 is cooled in counterflow heat exchanges (hex) by cool n2...

For this 19(a), The answer is 0.137 atm. My working is ##P_{gauge} = P_f - P_i## ##P_{gauge} = \frac{nRT_f}{V_f} - \frac{nRT_i}{V_i}## ##P_{gauge} = \frac{nRT_f}{V} - \frac{nRT_i}{V}## since volume does not change ##P_{gauge} = \frac{nR}{V}(T_f - T_i)## However, I am not sure how to go from...

I ran across the following problem : Statement: Consider a gas of ## N ## fermions and suppose that each energy level ## \varepsilon_n## has a multiplicity of ## g_n = (n+1)^2 ##. What is the Fermi energy and the average energy of this gas when ## N \rightarrow \infty## ? My attempt: The...

Hey everyone, I have an attempt at fully solving this problem (my final pressure is ##p_f = 5373,64 hPa##, final temp. is ##T_f = 303,15K = 30C##), but this exercise confuses me very much. First, I have not used the masses in my calculations and I'm pretty sure my prof. accidentally copypasted...

Well, it's been nearly 10 years since my last post, and it's been about that long since I've thought about ideal gases, so here we go :smile:. Description of Setup I have a system that uses compressed gas cylinders as a source to slowly purge an optical payload. The source is 12x compressed...

I want to work out how to calculate the pressure change in a gas cylinder if it is used to fill another cylinder to a lower pressure. For example, if a 50 litre gas cylinder initially at 200 bara is used to fill a 600 litre cylinder from atmospheric pressure to 1.5 Bara. What would the change...

For this problem, The solution is, However, why must we use absolute temperature for the ideal gas law (i.e why can we not use Celsius for T) Many thanks!

Obviously, we know intuitively what they mean, but it seems that physicists have developed an objective definition for all of these. If I were to guess, I'd say that: - a gas is vastly less compressible than a liquid or solid (i.e., which are considered in thermodynamics as basically...

Hi all, i'm the proud owner of a 1972 VW T2 Danbury Pop top campervan. Out of the factory these were fitted with 4 x long spring loaded struts which (when new) provided some lifting power to pop the roof up. Mine are now 50 years old and provide no assistance lifting / holding the roof in...

As in title: Plugging in the definition is straight forward, I am too lazy to type, I will just quote the book Fetter 1971: Up to here everything is very straight forward, in particular, since we are working on free electron gas, ##E=\hbar \omega## However, I have no idea how to arrive...

im learning thermodynamics and currently in a lesson about thermal processes. one process has constant pressure and before diving into equations or any proof the book provides a figure of a gas cylinder. the cylinder has a movable piston/lid on one side. the book then says "...and the piston end...

Hey there, Trying to confirm whether or not these substances emit formaldehyde gas when subject to heat of hair straightener and hairdryers. Both were ingredients in a keratin treatment i used at home and i had a crazy reaction (irritated skin, eyes, hair, nose and lungs) in the process of...

For part(b), My solution is, ##\Delta E_{int} = Q - W = \frac{3}{2}(P_fV_f - P_iV_i)## ##Q = W + \frac{3}{2}(P_fV_f - P_iV_i)## ##Q = 4000 + \frac{3}{2}((1 \times 10^6)(6 \times 10^{-3}) - (3 \times 10^6)(2 \times 10^{-3})## ##Q = 4000 J## However, according to the solution b. ##−4000 J## Can...

For this problem, dose anybody please give me guidance how they got 74 K as the answer? Note that chat GPT dose not give the correct answer (it gives the temperature of the gas is 1500 K). Many Thanks!

For this derivation, I am not sure why the bit highlighted in orange is not positive since the displacement of the piston is downwards in the same direction as the force applied. Many thanks!

An insulated container (constant volume, adiabatic) contains an Ideal gas with pressure P1 and temperature T1. We open the container's hatch for a few seconds and let some particles escape from the container, then we close the hatch again. We know container's pressure has reduced by exiting...

Question: Two samples of a monatomic ideal gas are in separate containers at the same conditions of pressure, volume, and temperature (V = 1.00 L and P = 1.00 atm). Both samples undergo changes in conditions and finish with V = 2.00 L and P = 2.00 atm. However, in the first sample, the volume is...

I'm reading through Hohenberg's seminal paper titled: "Inhomogeneous Electron Gas" that help lay the foundation for what we know of as Density Functional Theory (DFT) by proving the existence of a universal functional that exactly matches the ground-state energy of a system with a given...

I have considered two scenarios: 1) A particle that has just collided with the wall at ##z=L## is moving with a velocity ##v_z<0## moving away from the wall. Hence, the probability that this particle has of colliding again is ##0##, so its distribution is also ##0##. 2) A particle moving with...

I have been trying to make sense of the derivation of pressure under Kinetic Theory of Gases chapter, but it's not making sense to me when the impulse momentum equation is used for the collision between a gas molecule and the wall of the container. The book says that for the elastic collision...

Ref: Van der Waals Equation @ Wikipedia The above paragraph is explains how intermolecular attraction reduces the gas pressure, assuming that there is no attraction between walls and particles. In practice, would there be a change in pressure from one kind of wall to another, if we ensure...