Skip to main content

Questions tagged [volume]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
1 vote
1 answer
36 views

Volume preserving transformation in the Circular Restricted Three-Body problem

the Lagrangian of the planar circular restricted three-body problem in the rotating coordinate frame is: $$\mathcal{L}(x,y,\dot{x},\dot{y})=\frac{1}{2}(\dot{x}-\Omega y)^2 + \frac{1}{2}(\dot{y}+\Omega ...
Hajarl's user avatar
  • 11
3 votes
1 answer
62 views

Total differential of internal energy $U$ in terms of $p$ and $T$ using first law of thermodynamics in Fermi's Thermodynamics

While reading pages 19-20 of Enrico Fermi's classic introductory text on Thermodynamics, I ran into two sources of confusion with his application of the First Law. Fermi introduces a peculiar notation ...
user104761's user avatar
-1 votes
0 answers
25 views

Interpretation of Enthalpy when there is no $pV$ work done [duplicate]

Enthalpy tends to be defined as terms of a pressure volume work. I am looking at a one dimensional system where there is no $pV$ work and trying to get an intuition of enthalpy in this context. Can ...
Thomas Hayes's user avatar
1 vote
2 answers
83 views

Densities at a Point

I was recently reading Purcell’s text on electrodynamics. He generalizes Coulomb’s Law by introducing charge densities. However, what does the density at a point represent? (Since Purcell took charge ...
V T Naveen Mugundh's user avatar
0 votes
2 answers
87 views

Why do I get two different expression for $dV$ by different methods?

So, I was taught that if we have to find the component for a very small change in volume say $dV$ then it is equal to the product of total surface of the object say $s$ and the small thickness say $dr$...
Madly_Maths's user avatar
0 votes
1 answer
38 views

Water and ice, scales [closed]

There are scales with an identical bowl on each pan. We pour some amount of water into the first bowl. We pour less water and put an ice cube into the second bowl so the level of water in both bowls ...
Piotr H's user avatar
  • 23
1 vote
0 answers
48 views

Excluded volume in van der Waals' Equation

As per my understanding, excluded volume is defined as the volume excluded to the rest of the gas molecule's centers because of its presence. During bimolecular collisions, there is some overlap in ...
Marc Carlsan's user avatar
0 votes
1 answer
71 views

What does this equation for density mean?

What does this equation for density mean? $$\rho = \lim_{\Delta V\to\varepsilon^3} \ \frac{\Delta m}{\Delta V}$$
sebbbb's user avatar
  • 21
0 votes
5 answers
139 views

Why $VdP$ term omitted in isothermal Work?

Context: I'm asking about classical thermodynamics, that is "ideal gas", closed system, reversible processes etc. Why is the $VdP$ term omitted in calculation of work during isothermal ...
coobit's user avatar
  • 957
10 votes
3 answers
5k views

How much pressure would it take to compress a block of solid steel into one-tenth the original volume?

We all know to compress objects into smaller volumes, you would need to apply pressure to them. The required pressure depends on how strong the material is and which form is it (gas, liquid, solid). I ...
ZanMoon-chan's user avatar
0 votes
1 answer
37 views

Keeping sparkling water inside a bottle as aerated as it was before opening bottle

So when you open a new bottle of sparkling water (or soda) it's very fizzy and aerated. However, when it is stored for quite a bit (no matter how tightly you close the bottle cap) it loses some gases ...
bonbon's user avatar
  • 21
1 vote
0 answers
85 views

Quantization of charge implying charge exist in the form of point particles

The statement for quantization of charge says that total charge of a body is constant. Now the word " body " seems vague. We may consider any part of space which we want and call it a body. ...
Users's user avatar
  • 426
1 vote
1 answer
62 views

Why is the volume of an isolated system conserved? [closed]

Consider a system(S) + reservoir(R) that surrounds the system(S). The system(S) is not in thermodynamic equilibrium but the combined system (system + reservoir or say SR) is isolated i.e. the walls of ...
Shravan's user avatar
  • 11
0 votes
2 answers
54 views

Why lateral strain occurs when volume is not conserved on applying longitudinal stress?

I first thought that lateral strain occurs to conserve volume on applying longitudinal stress but later I realised that I was wrong. But now I have a confusion that why lateral strain occurs if volume ...
S K's user avatar
  • 45
0 votes
2 answers
146 views

Why is the work done by an expanding ideal gas $\textbf{P}_{ext}\Delta V$?

Consider an ideal gas in a cubical container as our system (only the gas is the system, not the walls of the container). If I understand correctly, if the gas expands at constant pressure $P_{int}$ ...
cloud's user avatar
  • 3
0 votes
1 answer
202 views

How to understand this Dirac delta function?

I am reading this paper about quantization of the electromagnetic field, and there is a point where the author imposes the fundamental commutation relation between the vector potential and its ...
Claudio Saspinski's user avatar
2 votes
2 answers
57 views

Electric current density definition

I'm just wondering why the current density $J$ is always defined as the amount of electric current traveling per unit cross-section area $J = \frac{I}{S}$, and not per volume unit $J = \frac{I}{V}$ so ...
ArziousYi's user avatar
1 vote
0 answers
34 views

How to calculate the flow of air that leaks out of a container?

I cannot grasp what should be a simple gas problem (last time I worked with gas formulas was 40 years ago). Values I provide here are just for the sake of explanation. There is a thermically isolated ...
Alex Poca's user avatar
  • 111
0 votes
2 answers
910 views

Why is an adiabat steeper than an isotherm in a $p$-$V$ curve?

What I have so far gathered is a mathematical explanation. Since for an adiabatic process, $pV^γ=$ constant, for a unit change in pressure, change in volume would be very less. Therefore, if compared ...
Mel's user avatar
  • 133
0 votes
0 answers
20 views

Does a locally volume-preserving deformation also preserves volume globally?

Is a locally volume-preserving deformation (in which the determinant of the deformation gradient (a.k.a Jacobian) is unity) is also globally volume preserving?
Naghi's user avatar
  • 167
0 votes
1 answer
54 views

Why is Volumetric stress change in pressure not final pressure?

While reading about volumetric stress, I found that volumetric stress on a body is equal to restoring force per unit area if force is normal to the surface and is proportional to the area. At ...
S K's user avatar
  • 45
-1 votes
1 answer
113 views

Why work is calculated by $Vdp$ when volume is constant in thermodynamics? [duplicate]

Why work is equal to $-VdP$ when volume is constant? Doesn't that imply that work is equal to 0? Isn't work a result of volume change?
Unicornsatemee's user avatar
1 vote
0 answers
45 views

Problem regarding open systems and a compression [closed]

Say we have a cylinder of height $h_0$ and transversal area $S_\perp$ filled with water vapour and covered by diathermic walls, as well as a mobile diathermic piston on the top, which is in contact ...
Ulshy's user avatar
  • 69
0 votes
2 answers
86 views

Confusion about the "Volume" in Archimedes principle

In Archimedes principle $F_b = \rho gV$. $\rho$ = density of fluid, $V$ = volume displaced by the fluid, and $g$ = gravity. If you have an object in the air, like a balloon, how does the volume work? ...
god david's user avatar
4 votes
1 answer
169 views

Number of fog droplets in the air

I have an issue with the official solution to this problem from BelPhO: Visibility on the road is 100 m. Assuming that the diameter of a fog droplet is 1 micron, estimate the concentration of fog ...
Bml's user avatar
  • 439
0 votes
1 answer
59 views

How is volume defined and measured in nuclear physics, in particular regarding the Sun’s core? [closed]

The Sun’s core is, from the micro/quantum perspective (from what I've read) the constantly moving phenomena of nuclear fusion (as the Earth is mostly the constantly moving phenomena of stable atoms ...
lars706's user avatar
  • 39
0 votes
2 answers
104 views

Enthalpy of a Van der Waals gas continuation

In my previous question Enthalpy of a Van der Waals gas, I got the expression of the enthalpy generalised, but I am still having issues finishing it since it might have some quite hard calculus... For ...
Ulshy's user avatar
  • 69
0 votes
1 answer
49 views

Doubt with the heat capacities

We know we can write the internal energy as: $$dU=\frac{\partial U}{\partial T}dT+\frac{\partial U}{\partial V}dV=C_v dT+\frac{\partial U}{\partial V}dV$$ and things started to not make sense, is it ...
Ulshy's user avatar
  • 69
4 votes
1 answer
156 views

Do neutron stars (or really dense stars) contain more volume inside of them than the expected $V=\frac{4}{3}\pi r^3$?

If I understand correctly neutron stars are so dense that general relativistic effects are not negligible anymore. Does this mean that the volume inside of neutron stars is bigger than we would expect ...
bananenheld's user avatar
  • 2,035
0 votes
0 answers
37 views

Volume element of the neighborhood of a surface

In this paper by da Costa, he derives the geometric potential arising due to the confinement of a quantum particle to a surface. However, I believe this physical context is not relevant to my question:...
AFG's user avatar
  • 2,284
1 vote
1 answer
72 views

Why do the litre and cubic metre volumes of cylinder natural gas not correspond?

A $47L$ cylinder says it contains $8.4m^3$ of natural gas at $137$ bar pressure. Could someone explain how we get from $47L$ to $8.4m^3$ ? I’m not an expert and thought they should be different by a ...
Gabi23's user avatar
  • 113
1 vote
3 answers
143 views

Evolution of volumes in Phase-Space

Liouville's theorem states that the volume occupied by an ensemble does not change as the ensemble evolves. My question regards the volume of the smallest sphere that contains the ensemble. Is there a ...
Antonio Bernardo's user avatar
0 votes
4 answers
92 views

Why are temperature and specific volume independent properties in thermodynamics?

If we have a sealed piston-cylinder with gas inside and we heat it from the outside, the temperature changes. At the same time, if we look at it as a control mass system,the volume increases as the ...
Rush's user avatar
  • 1
0 votes
0 answers
25 views

How does loudness decrease with distance? [duplicate]

Let's say there's a speaker in a huge open space on the Earth's surface. The speaker blares a sine wave with frequency $f$ Hz and and volume $V_0$ decibels. How does the volume (in decibels) decrease ...
chausies's user avatar
  • 1,090
0 votes
2 answers
380 views

Why do we usually measure liquids and gases by volume?

Why do measure liquids and gases in volume rather than by weight? Isn't that comparatively more inaccurate since volume changes with temperature and pressure?
ToLearn's user avatar
  • 49
0 votes
0 answers
77 views

Gauge symmetry and the volume in phase space

Recently, I am reading a paper about the soft theorem and large gauge symmetry which is non-zero in the boundary. In section 6, the author introduces the covariant phase space method to illuminate why ...
Lain's user avatar
  • 347
0 votes
0 answers
151 views

Why expansion work, $pdV$, is considered to be zero in nozzle?

Why $pdV$ work considered to be zero for flow of gas, say ideal gas, at low mach number through a converging adiabatic nozzle? [though total enthalpy remains constant, static enthalpy does change.] [...
GRANZER's user avatar
  • 649
0 votes
1 answer
44 views

Triple Integral of Volume Concentration

I am working on a problem involving volume concentrations which are defined as: $$ \phi_i=\frac{V_i}{V} $$ and are thus dimensionless. My problem is in $3$D and I have assumed that the components in ...
Mjoseph's user avatar
  • 143
0 votes
0 answers
90 views

Invariance of a volume element in phase space: What does it means?

I have been reading the third edition of Classical Mechanics by Goldstein, in particular, chapter 9 Poisson Brackets and Other canonical invariants. And it is shown that the magnitude of a volume ...
user353399's user avatar
1 vote
0 answers
88 views

Why $p= -\frac{\partial U}{\partial V}$?

In Callen's book, in page35 he defined $$p= -\frac{\partial U}{\partial V}$$ where does it come from? I thought it might come from a reversible process where $ dU=dQ+dW=TdS-PdV$(If the amount of ...
Raffaella's user avatar
  • 353
1 vote
1 answer
52 views

Calculate Change in Tank PSI per breath at depth

I am a scuba diver, trying to understand some physics that occurs throughout a dive. Primarily I am trying to understand the surface air consumption (SAC) derivation. For those unfamiliar, SAC is the ...
CMH12's user avatar
  • 25
4 votes
2 answers
166 views

Why chemists usually only deal with enthalpy and not internal energy? [duplicate]

From what I understand, enthalpy only seems like a mathematical intermediate step. Why do we have a special name for it?
Angry Granny's user avatar
3 votes
0 answers
274 views

Dirac delta in Fourier space for finite volume

In some class notes about cosmology I have found the following claim. The author starts by stating that the Dirac delta is given by: $$\delta^{(D)}(\vec{x}+\vec{x}')=\int\dfrac{d^3q}{(2\pi)^3}e^{i(\...
Wild Feather's user avatar
2 votes
3 answers
138 views

Dependence on $(p,V,T)$ rather confusing

I am currently taking the freshman thermodynamics course and have asked several times for explanations of the relationships which can, and which cannot, and why they cannot. But I still don't really ...
Masterrun80's user avatar
0 votes
0 answers
144 views

Does this theorem holds out for spacetime?

The theorem: Let $F$ and $C$ be two finite geometric figures (those defined by two continuous functions in a given region $D$), where $F$ belongs to an $n$-dimensional Euclidean space and $C$ is the ...
Antoniou's user avatar
  • 495
2 votes
0 answers
78 views

Haag’s theorem in finite volume

I’ve been reading on Haag’s theorem and found this proof that uses standard QFT instead of the axiomatic kind: https://arxiv.org/abs/2011.08875 It essentially boils down to saying that the vacuum ...
user avatar
-4 votes
3 answers
967 views

Area of a $pV$ diagram [duplicate]

On a $pV$ graph (where the Pressure is on the Y axis, and the Volume is on the X axis), I am conceptually confused on how the area under the graph is equivalent to the work done by the system (...
LottaQeustions's user avatar
1 vote
3 answers
1k views

How does Pressure times Volume = Work Done?

I understand the equation mathematically-- $p$ times (change in) $V$ = Work done. However, I am confused about it conceptually. Work is (in a non-calculus context) constant force applied over a set ...
LottaQeustions's user avatar
-1 votes
2 answers
116 views

Confusion on $pV$ diagrams

I am extremely confused on the concept of a $pV$ diagram. I understand that Pressure times (change in) Volume equals the Work done by a piston; however, I am confused on how volume and pressure can ...
LottaQeustions's user avatar
3 votes
1 answer
403 views

What is the "volume of the gauge group"?

I often see the term "volume of the gauge group" and I am not clear on what this is referring to. For example, in the second volume of Weinberg (page 22), he says ...the volume of the gauge ...
CBBAM's user avatar
  • 3,350

1
2 3 4 5
10