# Tagged Questions

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

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### Is it possible to have a line rather than a point where the three states of a substance can exist?

Most of us are familiar with state diagrams that define which of the three states a substance will take given the pressure and temperature. And that some substances, such as water for example, exhibit ...
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### Bernoulli Equation for isentropic ideal gas flow

If one derives the Bernoulli Equation for the isentropic ideal gas flow you get: $$\frac{1}{2}v^2 + g z + \left(\frac{\kappa}{\kappa -1} \right) \frac{p}{\rho} = const.$$ Two questions: Is ...
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### Pressure, density, volume and mass in a room

Here's the question. A window in the room is open. The next day, the temperature of the room has increased, but the pressure of the air stayed the same. State and explain what has happened to ...
112 views

### Triangular cyclic process [closed]

I am currently studying for my physics exam and I am trying to wrap my head around cyclic processes. There is the cyclic process: We know its an diatomic ideal gas, and the following variables are ...
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### Helium balloon stays on the floor

So yesterday I came back home with a buoyant helium balloon (no comment, and before you ask, it's blue) and I left it in the house. Obviously, it rose to the ceiling. This morning I woke up to a ...
2k views

### How does the bulk modulus of air change with rising pressure?

I can't seem to find the answer to what should be a trivial question: I have a rigid air-tight container of fixed volume and I am pumping air inside. The pressure is increasing (very slowly) from ~...
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### Can I always assume that a vapour pressure over a liquid is ideal?

Can I assume that the vapour of a subject over its liquid is ideal-ish? I'm thinking that if the vapour pressure is low the subject in question wont interact with itself, but it doesn't necessarily ...
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### Static pressure in ducts and its dependency on speed flow and density

I know that depending on the duct circuit (bends, complex geometries...etc), the static pressure will be defined. If we assume air is flowing in the circuit with varying speed and/or varying density. ...
85 views