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

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Weight of a material

I'm dealing with a problem here. Does a material lose weight when it transforms from solid to liquid? I believe it does. It loses weight because some of it becomes gas. Can anyone help me? Thank ...
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Distribution of refractive index of water when applied pressure wave

I was wondering when applying pressure wave, ultrasonic sound waves, under water, how I would be able to measure the distribution of the refractive index.
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Would you die before reaching the ground?

If you were to jump off a tall building, let's say Burj Khalifa, is it true that the pressure difference would be so strong as to kill you before reaching the ground?
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In a column of fluid does density vary?

In a column of fluid does density vary?
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How long did it take for the universe to become 1 one light year?

Given the density, pressure and other cosmological parameters. At this point we're not even thinking of time... But would this have occurred during or post Inflation? Could this be the Expansion ...
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Milky Way Density Profile

Does anyone know where I can find either a printed version or, better, a downloadable dump of data giving me the density profile of the Milky Way? I'm looking to put together a quick-and-dirty ...
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1answer
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Does tunneling transmission probability depend on the density of states or velocity?

In some quantum text books [1], the tunneling transmission formula depends only on the density of states of 2 regions (DOS) involved in tunneling. ($T(E) = C \times DOS_1(E) \times DOS_2(E)$, where C ...
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What is density? [closed]

Ok based on a mathematical stand point i get density im talking about a density in objects?how can one object with the same exact make up have a higher density? i have been reading about this for ...
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Alternative liquid for Galileo thermometer

So a friend of mine broke my Galileo thermometer recently. The glass tube and the liquid inside were lost, but the bulbs survived. I've cleaned out an old tall glass candle, and tried filling it with ...
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If hot air expands in all directions why is the balloon moving up?

A balloon is moving up. The hot air inside the balloon is expanding in all directions and cold air outside the balloon acts with force on the balloon from all directions (higher pressure force). Why ...
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29 views

Do different density objects in liquids affect net weight [duplicate]

I would test this but I have no tools to test it with. If I have a beaker of water and weigh it on a measure. Then I stick my fingers in the water (it doesn't over flow) does the weight change or ...
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What happens when electromagnetically shunken coin is heated

The question is simple: What happens to coin/object that was electromagnetically shrunken by a coin crusher device is then heated until it (I asume) melts? Do I have misconception or not just ...
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201 views

Why is density an intensive property?

I am still trying to understand what are intensive and extensive properties. Possibly someone can give a pointer to a decent text (preferably on the web), as I am not too happy (to say the least) with ...
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Determine the particle velocity of a pressure wave

I am using constant density wave propagators to model seismic waves in the subsurface. What I want with these acoustic waves is to estimate the energy of them at a certain grid point at a given time. ...
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125 views

Finding the density of gold crown using archimedes principle [closed]

Question: As shown in diagram below the crown has a mass of 14.7kg when measured above water and 13.4kg when measured in water. Is the crown made of gold? I have this following solution provided: ...
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1answer
33 views

Finding height of floating iceblock above seawater [closed]

This may be a very simple question but somehow I can't seems to solve it. For the sake of completness, I will use the same original question I am working on. Question: The density of ice is $917 ...
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Is there a material with non-monotone density dependence on pressure?

Is there a material with such non-linear effects (including chemical reactions, phase transitions etc ...) so that there would be range where pressure increase would yield density decrease? What ...
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1answer
55 views

The inverse square law of sound through solids?

We all know about the inverse square law of sound. In short the power of the wave will get evenly spread on an ever increasing spherical expansion and this will dissipate the power of the wave at a ...
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2answers
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Do we hear sounds differently on the highest mountains?

Some searching gives that above 6,000 meter altitude the air density is less than half of that at sea level. Speed of sound is about 15-20% slower and "acoustic impedance" seems to change too. Do ...
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Relativity and volume of black hole

Does Einstein's theory of special or general relativity incorporate volume? In a particle accelerator two particles smash together at relativistic speeds and "create" new particles (quarks etc) due ...
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1answer
167 views

Why is powdered sugar less dense than granulated sugar?

The density of powdered sugar is about 20% lower than that of granulated sugar. There is small composition difference between the two - about 3% cornstarch and 0.5% water in powdered sugar, but that's ...
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How to calculate the density of a polycrystalline sample?

I'm trying to figure out the density (g/cm^3) of La2CuO4. I know that the mass is 405.355 g/mol; what do I have to do to calculate the volume? Thanks!
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32 views

When things sink?

Why a heavy object over a less dense medium doesn't fall always to the bottom? Think: stone on balls of polystyrene. Why do the balls stick together and don't let the stone sink to the bottom? - ...
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3answers
193 views

Why $e$ in the formula for air density?

I am reading a book that says that the density of air is approximately $D = 1.25 e^{(-0.0001h)}$, where h is the height in meters. Why is Euler's number $e$ used here? Was a differential equation ...
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Hydrostatic pressure - doesn't density vary with depth?

Our class is learning about hydrostatic water pressure and we have been told that we can calculate the force of the liquid on an object at any depth using "the density x 9.8 x the depth". However, as ...
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How does the viscosity (besides density) of a fluid affects sinking

If water, air of whatever fluid had a different viscosity, but the same density, would things fall/sink differently?
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How come squeezing a water bottle makes the water come out?

This seems natural, but I can't wrap my head around it when I think about it. When I squeeze an open bottle filled with water, the water will spill out. When I squeeze a bottle, the material ...
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why exactly is ice less dense then water?

The answers to this question explain that ice is less dense than water because it has a "crystal structure", but they dont explain what exactly that is and why this happens, also I saw this answer ...
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Does the mass of a star change as it collapses into a black hole?

I know (I think!) that when a really big star collapses on itself it creates a black hole. My question: When a star collapses, is the mass equal to the mass of the star when it's not a black hole? Or ...
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Boundary conditions for the heat equation when solving a mass density gradient

I'm working with a mass density gradient with length $L$ and I'm trying to solve the heat equation in 1-D (mass diffusion equation, $\partial_t\rho(t,x)=D\Delta\rho(t,x)$), but I'm not sure which ...
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219 views

Does gravity cause Archimedes' principle and how?

Why do lighter objects float and denser sink? I understand this from the perspective that if the object can displace the equal mass of water it will float, but I wonder from the perspective of ...
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Why isn't jumping from a high altitude fatal?

After seeing this answer claiming that displacing matter "In a very short time", "no matter whether the matter is solid, liquid, or gas" (even though he concludes that falling from a high altitude is ...
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200 views

Do hail stone fall down just when it is created?

Density of ice is much higher than air. Then how can hail stone remain in earth atmosphere before they fall down ?
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Why is jumping into water from high altitude fatal?

If I jump from an airplane straight positioned upright into the ocean, why is it the same as jumping straight on the ground? Water is a liquid as opposed to the ground, so I would expect that by ...
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Finding a 1-Dimensional Mass Distribution

Past Discussion There have been a lot of questions and discussions regarding determining the mass distribution of various bodies through non-destructive purposes. Here are a few: Determination of ...
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Proton gas density

As far as I know the lightest gas is hydrogen due to low mass of its nucleus, but what if we were to somehow strip hydrogen atoms of electrons and enclose protons in a container made of teflon (high ...
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299 views

What makes water heavier than air?

I apologize in advance if this is too basic for this site. Considering that hydrogen is lighter then oxygen, and water is 2/3 hydrogen, and only 1/3 oxygen, and our "air" is comprised mainly of ...
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Effect of waters changing specific gravity on objects apparent weight placed in liquid

My goal is to monitor the change in specific gravity of a liquid over a period of time. My question is: What are the appropriate formula for determining expected apparent weight of an object immersed ...
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1answer
55 views

Hydrostatics , work Power and Energy [closed]

If a servant lifts 10 cubic meter of liquid from a tank, which is at a depth of 40m . If the work done by him is 1600J, then find the density of the liquid (g = 10 m/s^2)
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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 ...
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Why does sound travel faster in iron than mercury even though mercury has a higher density?

The speed of sound depends on the density of the medium in which it is travelling and increases when the density increases. For example, in solids sound travels faster than in liquid and even faster ...
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Compressed air in a volume: Can I determine its temperature?

Using a compressor, I augment the pressure in a volume (using atmospheric air). I only measure the pressure inside. I now that the density will increase however, the temperature decreases. Can any one ...
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Pressure versus Volume system problem

A rigid air tight container of volume 1.5 m$^3$ is filled with a gas of density 8 kg/m$^3$. The container has a density meter that allows us to watch the changes in density in the gas in the ...
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Is there a physically motivated “trick” to evaluate this convolution?

I'm working on adapting some of the formalism in this paper to a system I'm working with. The part I'm interested in amounts to convolving a density profile $\rho(r)$ with a smoothing kernel ...
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What does the absence of hydrodynamic entrance effects do to the momentum conservation Equation?

I am trying to do a homework problem where we re-write the mass, momentum and energy conservation formulas for downward flow in a vertical pipe and it says "where all hydrodynamic entrance effects ...
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Fluids and density [closed]

Is the answer C? Assume that you look at three objects that all float on water, but have different shapes and sizes. Which one has the greatest density? A.The object that has the largest fraction of ...
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concept of density in gravitational lensing

I may just be being very dense (no pun intended) but i'm reading up on gravitational lensing and it seems to require a notion of density (e.g. see here) I'm working on a question involving light ...
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Thermodynamics of thermometer

Mercury is used in thermometers because it increases in length significantly due to rise in temperature, However, mercury has high density relative to water, which means more inter-molecular forces ...
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157 views

Acting on a current density operator in second quantization

I have a current density operator in second quantization in the form: $\hat{J} = -i\left(\psi^\dagger \partial_x \psi - (\partial_x \psi^\dagger) \psi \right) $ operating on some state: $|\phi ...
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Does salt $NaCl$ as a solid float in molten salt?

I know ice floats in water because it's crystalline structure causes $H_20$ solid to be less dense than $H_20$ liquid. Is the same true for salt because it is crystalline? If not why?