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Density is defined as the mass per unit volume of a substance.

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How do I calculate the height of a given that a bubble rises from the bottom of the lake to the top of the lake? [on hold]

I am stuck on a physics problem which involves calculating the depth of a lake given that a bubble increases two times in volume as it rises from the bottom of a lake to the top of the lake. The ...
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0answers
79 views

Is $H_2O$ the only compound which has a density anomaly? [duplicate]

My question is simple: are there any elements, compounds or materials other than water ($H_2O$) which have a density anomaly characterized by a turning point in the $T-\rho$ curve?
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1answer
38 views

Should Copper 65 and Copper 63 isotopes have a larger density than a copper 29 atom?

I was looking at the first page of a paper (see https://aip.scitation.org/doi/10.1063/1.1735598#Metrics-content for details) and I ran across something odd. According to the paper, Copper isotopes 63 ...
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1answer
41 views

Does the optical density of a medium depend upon its mass density?

The optical density of a medium is quantified by its refractive index $n$. Does it have any correlation with the mass/number density of the medium? In other words is an optically denser medium must ...
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0answers
11 views

Density before black hole [duplicate]

I don't ask how dense a black hole is, but I do want to know, how dense does an object have to be before it becomes a black hole?
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3answers
58 views

Ocean density vs atmosphere density

I understand that the density of the oceans on Earth in on average constant regardless of the depth. It is 1020 kg/m^3 at the surface and 1050 kg/m^3 at deep waters. I understand too that this is not ...
40
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3answers
6k views

Can ants walk on liquid mercury? [closed]

I'm not a physicist, but I was wondering: Can ants walk on dense liquid like mercury and why?
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0answers
40 views

Using Helmholtz Free Energy to Calculate Liquid Density

My objective is to find an equation of state (EoS) for density, i.e. density as a function of pressure, temperature and concentration, for aqueous acids, bases and salts. A StackExchange user ...
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0answers
61 views

Deriving group velocity from restoring force and density

I have seen that in some cases one can derive the group velocity of a wave quickly by identifying the restoring force in the system and the density of the medium that the wave is traveling through (e....
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1answer
116 views

Why can't hot air balloons fly higher then helium balloons?

I have read these questions: Hot air balloon trajectory predictions Do atmospheric physics prevent hot air balloons from ascending over 60,000ft? What is precisely the reason that a helium balloon ...
1
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0answers
51 views

How does the temperature of water affect its refractive index?

I am aware this question has been asked many a time but i have never found a answer which satisfied my exact requirements. I recently completed an experiment on how refractive index is affected by ...
35
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1answer
9k views

Can I eat myself into a black hole?

This was a humorous thought experiment that occurred while chatting about black holes. The person that I was talking to assumed that a black hole required a specific density to be achieved. I pointed ...
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0answers
53 views

Expression of stress-energy tensor with density function

I try to get the following expression defining the stress-energy tensor in General Relativity ($\big< \big>$ means average) : $$T^{\mu\nu} = \int \dfrac{\text{d}^3p}{E} F(\vec{x},\vec{p})p^{\mu}...
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1answer
31 views

Can gas at near-vacuum densities pool at the bottom of containers?

Ordinarily, we assume that a gas expands to fill it's container, however, I've had the thought that at low enough densities, this may not be possible, because the force from pressure would not be ...
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4answers
68 views

Density and Gravity

Let's say we have two spheres. One is twice as dense as the other but they have the same mass. Were you to stand on the surface of each would you experience any difference in gravitational force or ...
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2answers
34 views

Torricelli's Law and Variable Density

I wish to explore a slight modification of a well known result found in several physics texts - Torricelli's Law of Efflux. The most common problem on the above result has the following setup: The ...
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0answers
44 views

Density of a perfect fluid

I'm puzzled over an equation used to predict the density of a perfect fluid. I am using this equation for CFD modeling using OpenFOAM. It is used as an equation of state for the liquid in a gas-...
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1answer
28 views

The approximate values of density for a flame with respect to heights

I'm aware that the difference in density with respect to height is low, but I'm in need of the values for a project: in which I explain that the continuity equation of fluid dynamics will work well ...
0
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2answers
55 views

Pressure under water considering bulk modulus

I want to calculate the under water pressure, taking into account the compression of water. I derived a formula, but apparently the function has a vertical asymptote, meaning that the pressure ...
0
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1answer
49 views

Density and refractive index of Water/sugar solution

I can't find a correlation or equation for refractive index of water and sugar solution of known density. Do you know where to find it?
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1answer
72 views

Diamond ring around black hole

I know that light takes longer to travel in a denser material, like diamond and I know that black holes also attract light. I was wandering what would happen if you would make a ring out of diamond, ...
0
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0answers
7 views

Measuring local properties in a suspension

Considering a fluid with a certain known concentration of particles (eg: 40% per volume RBCs in blood plasma), how do I measure analytically the speed of sound in the medium and its density? i.e. ...
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2answers
27 views

Does the density of water affect the speed of sea waves?

In the case of light waves, the denser the matter, the more slowly they propagate. Do the water waves behave identically?
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1answer
68 views

Neutron star matter density [duplicate]

Edit: Replaced black hole with neutron star, thanks to safesphere for his comment. We're told that tiny volumes of matter have huge mass in a neutron star. For the sake of argument, if you had a 1cm ...
5
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2answers
290 views

What atomic forces are acting to resist me pushing an air filled bottle underwater?

Yes air is less dense than water but how does the bottle know to rise or indeed to move? It's not electromagnetism I think. Does this have a relation to gravitational forces? Is it to do with the ...
9
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1answer
1k views

Can you make a metal denser by melting it and make it cool down under high pressure?

The answer is probably no. But can you make a metal denser by melting it and make it cool down under high pressure? Or would it just crack under internal stress when it returns to a solid? I'm going ...
3
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2answers
683 views

Hot air balloon - mass

Short background I'm aware that a hot air balloon rises up because of the less density than air. But I'm not sure about how that lower density is reached, and how it can be sustained over time. At ...
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0answers
29 views

How do I find out the net thrust produced by a propeller?

I am trying to find out the thrust that a propeller produces. Since a propeller can have various different types of inclination for it's blades as well as several parameters such as number of blades, ...
0
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0answers
9 views

Can I calculate the volume sputtering yield of a compound if I know the atomic component sputtering yields?

I'm running Monte Carlo simulations of a neon beam hitting a $\beta$-gallium oxide target. I set the initial bulk composition to be made of 40% gallium and 60% oxygen (Ga$_2$O$_3$). The simulations ...
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2answers
55 views

Can anyone explain centrifugation? [closed]

Why larger particles tend to remain at the bottom level of the test tube while the smaller particles form a layer above the larger particles?
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0answers
19 views

How much air does it take to lift the seeds? [closed]

I have a vessel with seed and water in side. The is a total of 6100 Lbs. and water is 523.6 Gals. the bulk density of the seed is 178 Lbs/CuFt. The water seed mix is expected to be 8' above the ...
0
votes
2answers
40 views

Definition of incompressible flow

What is the exact definition of an incompressible fluid flow ? Is it a flow with constant density OR Is it a flow with divergence free velocity field OR Is it a flow with Mach number less than 0.3? ...
0
votes
1answer
46 views

What is a black hole made of? [duplicate]

Since we know white dwarfs are made of electrons and neutrons stars are made of neutrons and quark gluon plasma. What can we say about the black hole in this sense since its properties are far ...
2
votes
2answers
225 views

What kind of matter are black holes made of?

Imagine a black hole originally formed from, for example, Rubidium atoms. On the other hand, one made from, for example, Helium atoms. Will it be there any difference between the two? Or perhaps once ...
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2answers
95 views

Calculating mass from the integration of the surface density of a disc

If I had an equation for the surface density of a disc as a function of it's radius, such as: $$ \Sigma = A\left(\frac{r}{B}\right)^{1/2} $$ where A and B are constants, and I want to find the mass, ...
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1answer
58 views

Properties of singularity

I read that singularity is point in space where is infinite gravitational force caused by collapsing something very big into something very small. How can something with certain mass (star few ...
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1answer
59 views

Applied physics to “fill the jar” problem [closed]

I think that the most of you are familiar with similar kind of problems / riddles: I always said that it depends upon the velocity with which the fluid comes out from the faucet. It doesn't seem ...
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votes
2answers
86 views

How does gravity affect density?

In massive objects, gas can be compressed, raising the density of the celestial body. Does this mean that if I create 100 stars and planets, all with the same density and random sizes, some of those ...
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0answers
37 views

Wood vs static Water

First of all: I'am not a physicist or anything close to it. I jhust enjoy to think about certain thinks in a different way and to ask for a much more detailed "how". So here is what keeps me from ...
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2answers
101 views

Why is it said that density of nucleons in a nucleus is constant? [closed]

I can not understand how we came to this conclusion, i did not find a satisfactory explanation in the literature.
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0answers
30 views

Black hole and particle law

After neutron degeneracy pressure the becomes a black hole. Before the black hole forms is there is no matter capable of resisting the gravitational collapse? If after black hole is formed then all ...
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0answers
35 views

Effect of aeration on Celerity

Suppose a ocean wave encountered a section of ocean which had a higher level of aeration from gas such as methane escaping from the seafloor. Due to the aerated sections apparent lower density would ...
0
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1answer
33 views

How to know wind speed, given the force

I'm doing a game that is set in a desert and there are sand storms that occur periodically. What I've done is very basic and far from realistic, which is ...
0
votes
0answers
29 views

How Can Somehing With Mass Have Zero Volume? [duplicate]

I am very under qualified when it comes to physics. So, please correct me if I asked a question that “can’t be asked”. With that being said, I ABSOLUTELY love astrophysics. Which is obviously ...
1
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2answers
134 views

How does an aspirator pump work?

The below picture is of a aspirator pump. If we press the bulb at A the air in it with density $\sigma$ will flow out with velocity $V$. This would cause lower pressure at B and hence the liquid with ...
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1answer
159 views

What is meant by a uniform body and continuous body in physics? [closed]

Is uniform mass and continuous mass is same as uniform body and continuous body? Examples of uniform, non-uniform, continuous and non-continuous mass/bodies? Please also explain a little bit. while ...
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3answers
109 views

Are all black holes singularities identical?

There seems to be a problem between a singularity and the event horizons size. My logic is this if u have two collapsing stars with different masses there horizons will be different in diameter yet ...
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0answers
26 views

Newtonian Fluid Waves

Suppose I have a wave tank partially filled with a shear thickening Newtonian fluid (Oobleck), on top of which sits a layer of water (separated by a thin membrane to prevent mixing) If I propagate a ...
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votes
1answer
251 views

Why does oil float on water?

This might be a silly question but I want to know why oil actually floats on water. I tried to explain it to myself using Archimedes' principle but that didn't help. Archimedes’ principle, ...
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1answer
44 views

How dense could an Earth-sized planet be before beginning to undergo fusion?

I'm trying to figure out the maximum possible density for an earth-sized planet before it would become an earth-sized star. To try to figure this out, I found a reference star, VB 10, known for being ...