# Questions tagged [ideal-gas]

A gas that behaves as randomly moving, non-interacting molecules. This allows a simplified equation of state.

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### Thermodynamic Problem: Heating of House with Open Windows

I recently ran into the following interesting problem I am now stuck on: $$S = \frac{n}{2}(\sigma+5R\ln\frac{U}{n} +2R \ln\frac{V}{n})$$ The air inside a house with open windows is initially in ...
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### Demonstrating the average dot-product of relative incident velocity with CM velocity of colliding pairs of ideal gas atoms is zero

In The Feynman Lectures on Physics Vol. I Ch. 39: The Kinetic Theory of Gases an argument is given in 39–4 Temperature and kinetic energy, showing that the average value of the dot-product of the ...
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### Understanding Feynman's development of the ideal gas law: Vol I 39-2 of The Feynman Lectures on Physics

In The Feynman Lectures on Physics, Volume I 39-2 The pressure of a gas, the following is presented: If $v$ is the velocity of an atom, and $v_{x}$ is the $x$-component of $v$, then $mv_{x}$ is ...
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### Air coming out of balloon

I have discovered recently that when we have a balloon in a room filled with air, with temperature $T_1$, and then this balloon gets a hole and air is let out, the temperature of the air that comes ...
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### Adiabatic expansion of ideal gas

I am considering a system with initial pressure $P_{A}$ and volume $V_{A}$. The internal energy $U_{A}$ should be zero. Then I have the following law for an ideal mono atomic gas $P^{3}V^{5}=const$. ...
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### Thermodynamics and gaseous state combination question

A water vapour filling the space under the piston of a cylinder is compressed (or expanded) so that it remain saturated all the time,being just on the verge of condensation. Find the molar heat ...
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### Wave equation on Air- Solid interaction

Suppose that there is, due to an explosion $h$ meters above the ground, a wave in the air with high density, velocity and pressure, capable of inducing an elastic wave on the earth's surface. How does ...
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### Why do aneroid barometers have error with temperature?

Altimeters use slightly evacuated (compared to atmospheric pressure at sea level) metal aneroid wafers. The wafers have a reference pressure outside the aircraft referred to as the "static port". ...
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### Why is the internal energy of a real gas a function of pressure and temperature only?

While studying thermodynamics, I read that the internal energy of an ideal gas is a function of temperature only. On searching the internet, i found an article which stated that the internal energy of ...
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### Isothermal compression without a heat reservoir

I have devised a method to isothermally compress a gas without the use of a heat reservoir. Consider a container of gas. To compress the gas normally, one would simply move one of the walls of the ...
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### Degeneracy in Maxwell Boltzmann distribution

While deriving Maxwell-Boltzmann distribution function we consider particles having degeneracy. But in classical mechanics how the concept of degeneracy of particle comes within?
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### Will the discrete emission of Green House Gases (GHG) increase the global temperature by an infinitesimal amount?

Suppose you take a trip with a gas-guzzling car on a Sunday. Will your action increase the global temperature by an infinitesimal amount?
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### Why are compressed air tanks cold? [duplicate]

Why is a compressed air tank cold to the touch when it’s in a compressed state before use?
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### Perfect gases and gravitational field

I have made this reasoning, thinking about it for a time but it's time to ask to you for comments / opinions and solider advices. Let's take a perfect gas: we know the temperature is related to the ...
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### Would a plane get lighter if dry ice is inside and it sublimes during the flight?

During a series of comments here, it was suggested that taking dry ice into an airplane, the airplane gets lighter as the ice sublimes. This was supported by the idea that when the dry-ice sublimes ...
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### Internal energy of an ideal gas?

From my past studies I have had the presumption that for an ideal gas the equation: $du=c_v dT$ ( where $du$ is the density of internal energy, $c_v$ is the specific heat capacity at constant ...
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### Why in an ideal gas as the volume increases, both the pressure and the temperature drop?

I was reading Fundamentals of Physics(Halliday, 10th ed.), chapter 19, when I saw a statement "Figure 19-15a shows our usual insulated cylinder, now containing an ideal gas and resting on an ...
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### Example of reversible isochoric process for an ideal gas

I’ve seen many books considering reversible isochoric processes performed by an ideal gas. But is that possible? Suppose I’ve a general isochoric process going from A to B, suppose I’m having a ...
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### Speed of Bubble in Coke

I was trying to solve the following problem, but my results seem illogical when I graph my solution. Assuming we have a bubble at the end of a coke glass, I want to solve for the speed of the bubble ...
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### Relating the maximum entropy with the pressure given in terms of volume

For a monoatomic ideal gas let the pressure of gas in a container be given as $p=p_0- \alpha V$ Where $p_0$ and $\alpha$ are constants and $V$ is the volume of gas. Then find the volume at which ...
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### Why is the work done by the system equal P external x (V final - V initial)?

Please See this video https://www.youtube.com/watch?v=j_6JxoL8qD4 Firstly, at 1:13 in the video, is the work done here by the system or on the system? Secondly, are V final(s) in both cases equal? ...
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### $h^3$ term in probability density function of ideal gas

Other than that we need the $h^3$ to 1) make the units correct and to 2) account for the normalization of the probability distribution, what interpretation can we give to this $h^3$ term in \begin{...
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### Does Humid Air Rise (neglecting the effects of weather turbulence-for example in a closed environment like a sealed room)

An internet search will find many people claiming that Humid Air (water vapor) rises. However, I am skeptical because if lighter molecules rose then, it follows that the air would be stratified by ...
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### How to find the work done by compressing gas?

What is the work done by the piston when the piston is compressed and there's no internal energy/heat lost from the gas(thermally insulated)? The reason I can't solve this problem is because I have ...
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### External or internal pressure in the gas laws

Does pressure in the ideal gas law and other gas laws (Boyle’s, Charles’s, and Gay-Lussac’s) mean the external or internal pressure?
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### Plotting a $PV$ diagram for free expansion — why is it undefined?

Apparently trying to plot a $PV$ diagram for an adiabatic free expansion of ideal gas is undefined. I'm taking issue as to why this is the case. From what I understand using my diagram attached as my ...
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### How was the ideal gas equation derived?

How did people come up with the formula: $$PV = nRT = k_BT \qquad$$? I see two possible ways: 1.) We did some measurements and defined $$kB:=\frac{PV}{T},$$ remarking that $\frac{PV}{T}$ is ...
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### Kinetic theory for Charles' Law: does frequency and time interval of collisions change?

So I was given this table in class about Charles' Law: The table I got from class says that the time interval and frequency of collisions increases. However, if the velocity of molecules and volume ...
A collection of $N$ point particles is held inside a cubic box of side $L$. The walls of the box are sticky. This means that when a particle collides with a wall, it stays attached for a short period ...