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1answer
26 views

Measuring cross-section area of a flexible tube (5mm dia approx)

I want to measure the avg. inner cross-section area of a flexible tube of outer diameter 5mm. Since the cross-section isn't a circle exactly, use of vernier caliper to measure inner diameter fails. ...
1
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1answer
66 views

Are subatomic partices n-dimensional hyperspheres or another n-dimensional shape?

This guy derives the formula for the volume of an n-dimensional hypersphere, which can also be found here on the Wikipedia page, and he shows that it is equal to this equation: $V_n = ...
0
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1answer
41 views

Density as a function of Temperature?

I know that volume = mass/density....and density is the function of temperature. Is there any standard equation that describes density as a function of temperature? The system I am interested in is ...
1
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1answer
56 views

Fluid Temperature as a function of Mass and Ambient Temperature

Problem I am trying to create an equation to calculate fuel temperature based on ambient temperature, heat exchange rate, and mass. The idea is very simple; when the mass is heated, depending on how ...
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3answers
191 views

Surface Area: Volume and its relation with heat

In biology, it is stated that more surface area and less volume helps for keeping bodies cool. How can one explain this phenomena in terms of physics?
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1answer
42 views

Does thermal energy change within a chamber depending on what's in it, where it is, what it is?

I have noticed that some people will say that, when you put more mass in an oven, it takes longer for both to cook than if just were one. Some others will say that timings are the same. Assume we ...
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2answers
86 views

Point masses and infinite densities

Point masses are masses who don't have volume. It is said that they are infinitly dense, but I though division by zero is undefined hence you can't define the density for a point mass because ...
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0answers
84 views

Formula for residence time/turnover rate with unsteady state

I'm not sure this is the correct place to ask my question... but maybe someone could still help me. I'm looking for a way to calculate the residence time/turnover rate. I have the production and ...
0
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0answers
258 views

Mass, Volume, Density, and Pressure of Balloon Inside a Balloon

I'm not a physics guy so I'll apologize from the start if I put some erroneous terms. I just want to know the relationship of mass, volume, density and pressure of the two balloons if balloon A is ...
2
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2answers
704 views

Why is it faster (as in proportion to volume) to boil 4 cups of water than to boil 2 cups?

I did an experiment where I boiled two cups (500ml) of water in a kettle, and it took 1:30 minutes to reach around 98 C, average. However, when I boiled 4 cups of water, (1L) it only took me 2:30 ...
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0answers
82 views

Over-inflating weather balloons

Would it be safe to over-inflate a weather balloon if it isn't going to be used at high altitudes? I've been looking at several different balloons, but they are all measured by their burst diameter ...
5
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2answers
151 views

What is the entropy of a system when its volume tends to zero?

Say that a closed system has $n$ dimensions and is in the shape of a $n$-ball with a radius of 1, it's volume will be $$\frac{\pi^\frac{n}{2}}{\Gamma(\frac{n}{2}+1)}$$ which tends to 0 yet is not ...
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2answers
810 views

How is it possible to equate the internal energy at constant volume with the internal energy of an adiabatic process?

I hope my question makes sense. My problem is that, I have read through numerous textbooks that nC(cons. volume)dT = -PdV when deriving the relationship between T and V for an adiabatic process, ...
6
votes
2answers
551 views

Do black holes have infinite areas and volumes?

How to calculate the area / volume of a black hole? Is there a corresponding mathematical function such as rotating $1/x$ around the $x$-axis or likewise to find the volume?
11
votes
1answer
543 views

Why does my natural whistle have a maximum volume

When I whistle, I find that I can vary the volume by pushing more or less air through my mouth at once. However, when I increase volume past a point, I start to hear a blend of rushing air and a ...
2
votes
1answer
518 views

Thermal expansion of Sphere

How would one go about writing an expression of the expansion of the volume of a sphere of a given material? I noticed a few sources give it as $\Delta V= 3\gamma V\Delta T $ where V is the initial ...
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vote
3answers
323 views

Does the volume of a thermodynamic system always have to change for it to do work?

Does the volume of a thermodynamic system always have to change for it to do work? If yes,could you explain why? And if no, could you provide the example of a system, where it is not neccesary.
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3answers
5k views

Thermodynamics - Sign convention

I use the sign convention: Heat absorbed by the system = $q+$ (positive) Heat evolved by the system = $q-$ (negative) Work done on the system = $w +$ (positive) Work done by the system = $w -$ ...
2
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2answers
172 views

The physics behind The Great Flood [closed]

The book of Genesis floats (pardon the pun) some interesting numbers when discussing the Great Flood. For example, it rained for 40 days and 40 nights, and at the end of that time, the entire planet ...
0
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1answer
344 views

What is the particle residence time for given flow rates of gas mixture components?

For two different chemical substances there are two open valves with flow rates $$Q_1=a\frac{m^3}{h}\ \text{ and }\ \ Q_2=b\frac{m^3}{h},$$ leading into seperate cables. Next, the cables join, the ...
3
votes
2answers
156 views

The appearance of volume $V$ in the Fourier series representation of a periodic cubic system

In the textbook Understanding Molecular Simulation by Frenkel and Smit (Second Edition), the authors represent a function $f(\textbf{r})$ (which depends on the coordinates of a periodic system) as a ...
1
vote
1answer
2k views

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 ...
2
votes
1answer
560 views

Gas Cylinder Life

Say I have a gas cylinder filled with nitrogen to some volume at some pressure. On that cylinder I have a regulator so that I get a steady pressure out. I wish to discharge the cylinder. How many ...
8
votes
2answers
301 views

Do you pay more for gas when the day is warmer?

Found this at the gas station yesteday - got me thinking...
2
votes
4answers
4k views

What kinds of materials contract the most in cold temperatures?

I know that water expands in the freezer, but I'm curious about which materials contract in response to cold temperatures --- and most importantly, which ones undergo the most drastic changes?
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4answers
15k views

Why are volume and pressure inversely proportional to each other?

It makes sense, that if you have a balloon and press it down with your hands, the volume will decrease and the pressure will increase. This confirms Boyle's Law, $ pV=k=nRT $. But what if the ...
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2answers
146 views

How does cooling scale with volume?

What equation would give me the answer to the question, "If i have a cup of water at a tempature of say boiling, how long would that cup of water take to cool off compared to say half that size of a ...
0
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3answers
194 views

What is the volume of a parcel of air of a giving weight at average sea level pressure

I know this is probably some basic math once you have the figures, but my Google-fu is failing me. Say I have 5 pounds of air. Air meaning, the typical composition of the atmosphere of Earth. And by ...
5
votes
1answer
360 views

Why is the Haar measure times the volume of the eigenvalue simplex considered a good measure of Hilbert space volume?

In particular, why do we need both of these to find the volume? And should I be thinking of it as an actual volume or not? This Hilbert space volume is talked about in this paper. It says There ...
6
votes
4answers
2k views

Finding the volume of this irregular shape I have

I have an approximately basketball-sized non-hollow piece of aluminum sitting in my house that is of irregular shape. I need to find the volume of it for a very legitimate yet irrelevant reason. ...