# Questions tagged [volume]

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### What is the atomic composition of the human body, by volume?

According to Wikipedia, the composition (by atomic percent) of the human body is: 62% hydrogen 24% oxygen 12% carbon 1% nitrogen etc. Question: What is our volumetric composition*? *I get this is a ...
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### Proving the rate of volume of flow of water through an inclined area

We have studied that volume of water flowing per second through a given area $a$ is v.a, where v is the velocity of water. I have tried to prove the same. I assume that a square area of side a metre ...
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### Sanity check on meaning of Liouville's theorem

I've been studying Liouville's theorem lately. The statistical mechanics textbook by Kardar proves the theorem by showing that $dq\cdot dp$ is unchanged for each coordinate for an infinitessimal ...
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### Is the total volume proportional to the number of identical sound sources?

What happens to the perception of loudness when 4 identical devices placed around the listener play a sound sample? Will they sound 4 times "louder" than 1 device? What if they're a bit out ...
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### Measure volume/mass of a bag of water without weighing scale

I am trying to figure out the mass and/or volume of liquid inside a sealed plastic bag of about 150 litres (1x0.6x0.3m) without being able to use a weighing scale. Preferably, the measurement devices ...
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### Is there any formula showing the relationship between $V$, $A$ and $G$ as mentioned below?

We all know that if we fill a cylinder with water and then drop the egg into the water it sinks but when we add some three tsp of salt the egg floats. Let, $V=$ volume of the cylinder. $A=$ Volume of ...
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### Energy density of a 0D point particle vs. a 1D string

As I understand there is a problem in physics where point-like massive (or charged, etc.) particles would have infinite mass/energy (or charge, etc.) density. I'm curious how in the context of String ...
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### If gases are not ideal at high pressures, why doesn't raising the temperature of a gas make it less ideal?

I'm learning about ideal and non-ideal gas behavior in Chemistry, and my textbook and online sources say two things : Gases behave ideally at high temperatures and low pressures. Gases behave non-...
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### Does multiple outlets (at same level on tank) from an overhead tank increase pressure?

I have a tank that is about 1foot high from my shower, however the pressure(or volume) isn't sufficient. Is it possible to increase the pressure(or volume) at the showerhead by doing the following: ...
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### Relation between surface area/shape and pressure

For a shape with a given volume and given gas pressure inside the volume, if the shape is changed to increase the surface area, will the internal gas pressure change?
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### When differential of $p$-$V$ $dW$ work equals $-pdV$?

The differential form of the first law takes the form $$dU=\delta Q + \delta W$$ or $$dU=TdS-pdV.$$ First, we know that $TdS=\delta Q$ for reversible process. So we can't say that $dU=\delta Q -pdV$. ...
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### What causes volume of sound to decrease with distance?

I know about the inverse square law however I do not know why it actually decreases. Does it have to do with sound absorption, it runs out of energy so the vibrations lessen or as distance increases ...
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### Inmersion of homogeneous straight cone into a liquid

I have a problem with an exercise that I require help: Find the immersion of a homogeneous straight cone of height h and specific weight $\gamma_1$ in a liquid with specific weight $\gamma$. The ...
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### Is it a coincidence that 1 liter water has a mass of 1 kg while 1 cubic meter has 1000 liters of water?

1 cubic meter has 1000 liters of liquid. Meter is a unit independent of kilogram. Then why does 1 liter of water at max density (4 °C) have a mass of 1 kg? Is it a mere coincidence?
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### Lost volume data of water and isopropanol mixtures [closed]

WHO has two recipes for disinfecting, based on ethanol and isopropanol (IPA). They typically start with an alcohol volume and then top it off with the other ingredients to 10 litre. One of the recipes ...
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### Why do some textbooks use $T$-$V$ diagram for temperature table instead of $p$-$V$ diagram?

I am confused about this thing. In the temperature table, the first column explains specific temperature and the second column explains corresponding saturation pressure. From what I understand, if ...
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### In which dimension should nearest neighbor distances be calculated? Confusion regarding some concepts

In this paper, Abstract—The intrinsic dimensionality of a set of patterns is important in determining an appropriate number of features for representing the data and whether a reasonable two- or ...
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### Why is tire pressure lower when parking and higher while driving (and not rise more when driving faster)?

I just noticed this whenever I park the car for a while, the tire pressure goes to a lower value on all tires, and whenever I start driving, it goes higher. The difference is not so big, but it is ...
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### Calculate mass of air in a tyre from pressure

How can one calculate the mass of air inside a tyre, given a particular tyre size; a pressure, in $kPa = \frac{1000kg}{m\cdot s^2}$; and assuming room temperature, and normal air composition? I can't ...
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### Crossings in the $p$-$V$-diagram of Thermodynamic cycles

Today I was tasked with correcting and grading a first year thermodynamics exam and one student drew a very peculiar diagram for the Ericsson-cycle. In the p-V-diagram the isothermal expansion and ...
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### Time period of piston performing SHM

Suppose I have a closed piston-cylinder system which contains an ideal gas,and it is being compressed adiabatically by the piston which has a vertical orientation,and in doing so,the piston is ...
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### How can a Diesel motor be drawn on a $pV$-diagram?

Only quasi-static processes can be drawn on a PV-diagram, because during a quasi-static process thermodyanamic variables such as pressure $p$ and volume $V$ are well-defined. However, for example, the ...
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### What Are The Physics and Air Pressure Effects of Extremely Large Bells

How would one go about figuring out the physical properties of when a bell is hit. Can I parameterize the diameter of the bell, its height, and the kinetic force of the knock to get the volume in ...
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### How does the distribution of entropy in the expanding universe evolve? [duplicate]

Also, Is the entropy divided by the volume of the (observable) universe increasing with respect to time or is that number decreasing, unstable, or constant, or infinite?
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### Intuition of $dV$ in $PdV$?

I seem to have some misunderstanding of $PdV$ in the first law of thermodynamics. $$P dV = T dS - d U$$ I have a ballon. I apply some work (or change the temperature inside the balloon). Now, ...
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### Volume form in terms of the Levi-Civita Symbol

I'm currently reading Sean Carroll's book on General Relativity, and at some point he writes: First notice that the definition of the wedge product allows us to write \begin{equation} \mathrm{d}x^...
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### Particle states per phase space volume of a quantum gas

Consider a quantum gas in a box with volume $V=L^3$ and temperature $T$, consisting of spinless bosons. Explain why the number $dN$ of "single-particle states" in a "momentum space volume" $d^3p$ is ...
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### Boyle's Law and hot air balloon

A bit dumb question because it is really difficult to imagine it. :- Pressure is force per area. Talking about gases, the pressure is said to be the force molecules exert on walls of let's say a ...
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### Demonstration of comoving volume between 2 redshifts

1) I can't manage to find/justify the relation (1) below, from the common relation (2) of a volume. 2) It seems the variable r is actually the comoving distance and not comoving coordinates (with ...
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### Virial expansion in terms of pressure

I'm studying thermodynamics and I found two forms for the virial expansion: $$pV~=~RT[1+\frac{A_2}{V}+\frac{A_3}{V^2}+\ldots] \tag{1}$$ and $$pV~=~RT[1+B_2p+B_3p^2+\ldots]\tag{2}$$ my problem is that ...
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### Change in entropy due to the change in volume

If its given that $N$ no of Ideal gas atoms are in $V$ volume. What will be the change in entropy in units of $N\cdot kb\cdot\ln2$ when the volume is increased fourfold, i.e. $V \to 4V$, keeping ...
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### What is the volume inside the inner event horizon of a Kerr black hole?

(Dokuchaev 2011) found periodic orbits of particles and photons inside a Kerr-Newman black hole with a maximally extended global geometry. They orbit inside the inner horizon $r<r_-$ where the $r$ ...
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### Pressure and volume [closed]

Currently, I am working on this experiment where I hit a balloon with a small object so that the pressure inside a balloon changes. The pressure increased when I hit the balloon, but I need to ...