density's questions - Chinese 1answer

464 density questions.

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}...

The center of a black hole is a singularity. By definition, a singularity has infinite density. So how can a black hole with a different mass or density be described?

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 ...

I am referring the paper on GERG-2008 equation of state. I am interested in calculating the properties of ideal mixtures of real gases. The GERG-2008 EOS is in Helmholtz free energy and hence the ...

I am aware that at present the density parameter has a value very close to one. Does this parameter change over time, and if so how does that affect the fate of the universe, in terms of open/closed ...

I am in class $9^{th}$, I'm reading my physics book in which it is written that: $$\mathrm{Relative\ Density} = \frac{\mathrm{Weight\ of\ solid\ in\ air}}{\mathrm{Loss\ of\ weight\ of\ solid\ in\ ...

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?

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, ...

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. ...

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

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 ...

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 ...

Basically, I'm using the equation $\frac{F}{A} = -B\times \frac{\bigtriangleup V}{V_o} $. Originally I had to find the change in volume given an initial volume (B and pressure ($\frac{F}{A}$) were ...

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 ...

Clouds are made up of tiny water or ice droplets, depending on temperature. This implies that cloud density is greater than that of dry air. Why don't clouds sink through their surrounding atmosphere ...

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 ...

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, ...

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 ...

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?

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 ...

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 ...

I just read this answer on EE.SE and that triggered a doubt in me. If I were asked whether there is any relationship between the electrical resistivity and the density of a substance I'd answer ...

According to many authors, a fluid is defined to be incompressible if the material derivative of the density $\frac{D\rho}{Dt}$ is zero, that is to say, that in an frame of reference following the ...

What is meant by incompressible flow? The density of the fluid is a constant, $\rho = constant$ The density of a fluid has a spatial dependence but remains constant in time, $\rho = \rho(\mathbf{r})$ ...

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? ...

It is well known that water at 4C is denser than water at 0C. This is the usual explanation for why a body of water freezes from the surface (also it's because ice is even less dense, but that's ...

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 ...

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 ...

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 ...

I often find this affirmation when scientifics reffer to black holes: "A black hole is so dense that even light cannot escape from it" Does this mean that there is a relationship between density and ...

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, ...

Why is Earth's gravitational pull only at its center? Does acceleration due to gravity remain constant wherever I go in and on the Earth?

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 ...

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

Second, related question: does water density relate to, or cause, water pressure? Everyone I talk to dismisses the idea that water density substantially affects pressure, and emphasizes that water is ...

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 ...

According to Schwarzschild metric: $$ c^2~\mathrm d\tau^2 = \left(1-\frac{r_s}{r}\right)c^2 ~\mathrm dt^2 - \left(1-\frac{r_s}{r}\right)^{-1}~\mathrm dr^2 - r^2\left(\mathrm d\theta^2 + \sin^2\theta~...

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 ...

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 ...

Why does there have to be a singularity in a black hole, and not just a very dense lump of matter of finite size? If there's any such thing as granularity of space, couldn't the "singularity" be just ...

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 ...

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