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

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Nucleon-nucleon collision density

Can someone help me derive expression for nucleon-nucleon collision density as a function of transverse plane coordinates (ultra-relativistic heavy ion collisions) using Wood-Saxon nuclear densities( ...
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Measure density with the help of buoyancy

I am trying to derive a formula to calculate the density of a irregulary shaped object. I can measure the (false) weight of the object in pure air (of known density), and the (false) weight of the ...
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If hydrogen and helium are lighter than air, why won't liquid hydrogen and liquid helium defy gravity?

Title says it all. If hydrogen and helium are lighter than air, why won't liquid hydrogen and liquid helium defy gravity?
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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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is gravitational force dependent on objects radius?

I was told that objects with the same mass but different sizes (or densities) will have a different gravitational pull. Is this true? If so, why?
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What causes liquids to have different densities?

We know that different liquids have different densities and it is mass over volume. When the mass is more, then its gravitational attraction will be higher (Compared to other lighter atomic mass ...
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617 views

Density of Air in a balloon

A balloon with volume 2800 m³ is heated up to 60 °C. If the outer temperature is 12 °C and the air has a pressure of 960 hPa, what is the density of the air inside the balloon and on the ...
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Center Of Mass Troubles

I understand the concept of Center Of Mass(com), but I am having a difficult time interpreting the equation of the simplified case of one-dimension. The book I am reading defines the position of the ...
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503 views

How to correctly solve density tolerance

I want to know if my solution to a textbook problem has any major problems with it. Here is the problem: Ethanol has a given density of 0.789 g/mL at 20 degrees Celsius and isopropanol has a given ...
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Definition of torque for a continuous body

I am working on basic physics definitions. Given a particle at position $r$ (in some coorinate reference system) upon which acts a force $F$, the $torque$ $\tau$ is defined by \begin{equation} ...
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69 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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34 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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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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109 views

Density of a material in different dimensions

Hope this isn't something trivially wrong, I am a beginner in classical mechanics. But anyways, say there is a cube, of side length $a \ \text{cm}$. The volume of the cube is $a^3 \ \text{cm}^3$. If ...
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Temperature and density

As temperature rise the density become lower,When temperature goes down, density is higher but in higher temperature the body become bigger so why density become lower?
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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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43 views

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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68 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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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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111 views

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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464 views

Archimedes' principle for two liquid layers

Problem: I have a cylindrical vessel of height $H$ and radius $R$. There are two liquid layers in the vessel. The first has density $D_1$ and height $h_1$, the second has density $D_2$ and height ...
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344 views

Possible Rock Density Determination Method

I am trying to do density determinations on a large number of individual rock samples. I know the standard dry weight - wet weight methods but have an idea that might be better. I can buy a ...
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125 views

Energy transfer by a rotating disk at a constant RPM

Does Energy transfer from a rotating disk at a constant RPM into ambient fluid depend on disk material density? Why?
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619 views

Linear charge density, surface charge density and volume charge density

What is the difference among: linear charge density, surface charge density, and volume charge density?
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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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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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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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325 views

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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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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182 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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What is the electrical field of a capacitor plate as a charge approaches

The electrical field for a charge density $\varrho(r)$ is $${\bf E}({\bf r})=\frac{1}{4\pi\varepsilon_0}\int \varrho({\bf r}')\frac{{\bf r}-{\bf r}'}{\hspace{.1cm }|{\bf r}-{\bf r}'|^3} \mathrm ...
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271 views

How to calculate flux density in a toroidal CT that has an electrical line pass through the center?

I have seen the Biot–Savart equation, but I don't know how to apply it. Does the conductor length need to be considered finite and equal to the core length, or will the calculation be for a conductor ...
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In a glass of water, will an ice cube ever touch the bottom?

No matter the mass of the ice cube or the level of the water, will the ice cube ever touch the bottom of the glass or will there always be a layer of water in between?
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60 views

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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134 views

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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206 views

Suppose a hollow metal sphere filled with helium is dropped in a body of water

What are the conditions that would cause said sphere to sink or float? What if the sphere was full of ice instead?
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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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476 views

Percentage of water that is void or empty space?

At the atomic level, at sea level on earth, what percentage of normal pure drinking water is void or empty space? What percentage of lead (the kind used to insulate from nuclear radiation) is void or ...
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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 ...