Questions tagged [density]

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

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Density of granulated cane sugar

What is the density in g/cm3 of cane sugar, for example in the following product: https://www.amazon.com/gp/product/B01LYMXK56 ?
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van der Waals equation of state

I understand where the van der Waals equation originates from, but I am having trouble understanding why it underestimates liquid densities. Could someone please explain? And when is it not ...
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Consider a cube of ice with volume equal to 3cm³ and a fixed density equal to 916g/cm3, How many of the molecules are in the surface of the cube? [closed]

This was a question that my fluid mechanics teacher ask today in class, I find the number of total molecules, and then my teacher says that we could search the size of one $\rm H_2O$ molecule, then I ...
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Is buoyant force self-adjusting?

Assume that density of the body is less than the fluid. If we put a body in a given fluid the buoyant force equalise the weight of the body. If we increase weight, the buoyant force increase? If it ...
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Total charge from a charge density

I was trying to calculate the total charge from a charge density that has a very strange form involving delta functions. The charge density is $$\rho(\vec r) = - \vec d . \nabla \delta(\vec r)$$ $d$ ...
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Order balls by their density

I have a bunch of solid balls, each ball has a different diameter, a different mass and made from different material. I can compare if one ball is heavier than another ball or if one ball is bigger ...
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1answer
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Why the inner core of planet Earth is not composed of the densest materials?

I read on various sources the inner core of our planet is said to be mostly composed of a iron-nickel alloy, plus some lighter elements like silicon. On the other hand, I know that in general lighter ...
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Why does a floating object displace more substance than a sunk object? [duplicate]

Consider a box floating on water having a coin on top, now suppose after some time by some external influence, the coin is dropped into water. After doing the calculations, to my surprise, I found ...
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What are examples that will further explain the relationship of density to mass and volume, when mass is uniformly distributed? [closed]

Examples that will further explain the relationship of density to mass and volume, when mass is uniformly distributed.
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Cross correlations between 2 sensors - Approximation of a 2D + 3D synthesis

I am interested, in the context of my work, in the cross correlations between a spectroscopic probe (which gives a 3D distribution of galaxies with redshifts, which is also called spectroscopic Galaxy ...
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Will a plastic feel less heavy when I put it in a bucket of water and carry it?

If I'm carrying a bucket of water in one hand and a piece of plastic in the other, and then I decide to keep the plastic in the bucket of water (it floats). Will it feel less heavy in the second case? ...
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If the integral diverges while finding the expectation value

I was wondering what the expectation value of a wave function might be if the corresponding integral diverges. For example, if I graph the probability density $\Psi (x) = \sqrt{\lambda/\pi} \exp(-\...
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Relationship between density of water and temperature

How can I find the different temperatures of the water with the same density? Eg, At approximately what other temperature does water have the same density as at 1∘C?
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Does squeezing a bottle of beer/soda helps from going flat?

I would like to resolve a dilemma of squeezing or unsqueezing a bottle of beer/soda in order to keep the beer/soda for as long as it is possible from going flat. I would like to ask 3 questions that ...
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Density in solid angle $\Omega$ convert to spherical angles $\theta$ and $\phi$

I was given a probability density $$ \frac{dP}{d\Omega} $$ where $\Omega$ is the solid angle such that $$ d\Omega = \sin \theta \ d\theta \ d\phi $$ and $\theta$ and $\phi$ the sperical coordinates ...
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Mass-density functions: how is there mass-density at points?

We often discuss mass-density, charge-density, and other such functions: $\rho(x,y)$ for ultra-thin plates and $\rho(x,y,z)$ for 3-d objects. The units for the output of these functions say mass or ...
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Does matter follow the curvature of space-time?

How is matter affected by the warping of space-time? Does it expand and contract, follow the curvature of space? What happens the shape/volume/density of matter when it enters a gravity well, or ...
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What is the relation between energy density ($\Omega$) and the number density of neutrinos ($n$)?

What is the numerical relation between energy density ( $\Omega_\text{s}, \Omega_\alpha$), and the number density of neutrinos (sterile - $n_s$ , active - $n_\alpha$)? Background info that might help ...
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If a material less denser than the earth’s core were at the center of Earth would it move towards Earth's surface?

Maybe it is easy but I am fairly confused. If a bubble of gass is 1m deep in the sea when left go will move up due to gravity pulling down havier water molecules. All is explained by the law of ...
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What happens to weight when ice melts? [closed]

A block of ice is weighed in a container. Then, it is left out to melt. Would the weight of the water be greater, less than, or equal to the ice? I know that it has something to do with density and ...
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1answer
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how to calculate how high would a helium balloon with weight go? [closed]

I knew that one liter of helium would lift approximately 1 gram of mass. However, I could not find how to calculate how high would that 1 gram go. Imagine if we have a helium balloon (ignore the ...
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If the Sun shrunk to the diameter of the earth, would Earth be habitable? [closed]

I was thinking about the sun. What if it shrunk in diameter to the size of the Earth? It wouldn't change the gravity much. But would it change the heat? If so, would the earth become uninhabitable? My ...
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Shake water and seed oil: color and density

These days I am spraying the leaves of my garden, to prevent insects, mixing strongly water and soya oil. The color has become all white. Soy oil has a relative density of $0.915 \div 0.925$ kg/dm$^3$...
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Will the metal block will sink or float in the following case?

We know that $\text{density}= \frac{\text{mass}}{\text{volume}}$, and density of water is $1000\, \text{kg/m}^3$. If I want to float a $100 \,\text{kg}$ metal block then using the above formula of ...
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What are the benefits and reasons behind considering a probability density distribution for electrons as opposed to a mere density distribution?

Before now, I had never questioned this matter. Why must we assume a probability density distribution (pdd) as opposed to a general density distribution (gdd)? Perhaps I have a misunderstanding. My ...
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In the electron density, what exactly do you mean by $\sigma$ mathematically?

Suppose there is a many-body eigenvalue problem $$ H(r_1,\cdots,r_n) = - \frac{1}{2} \nabla^2|_{r_1\cdots,r_n} + V(r_1,\cdots,r_n). $$ This potential is symmetric and the hamiltonian does not depend ...
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If you were to have an empty balloon, would it float?

Okay, I really have three questions, but I can only post once every 40 minutes and they’re all related. Say I have a balloon with the inside supported by a collapsible frame and made from a very ...
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Is there any formula showing the relationship between $V$, $A$ and $G$ as mentioned below?

We all know that if we fill a cylinder with water and then drop the egg into the water it sinks but when we add some three tsp of salt the egg floats. Let, $V=$ volume of the cylinder. $A=$ Volume of ...
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How to infer about the volume of the body from measuring the mass of the object in 2 different liquids?

While solving a problem on hydro statics subject I saw a statement that argued that if I know the weight of the object in the air and then I know the weight of the object in the water.so when I ...
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Compute the fermion number density

Consider fermion DM with g internal degrees of freedom and the statistical distribution results in: $$f(E) = \frac{g}{ \exp[(E − µ)/T] + 1}$$ with $g = 1$ when $E < µ$ and $g = 0$ when $E > µ$ ...
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Formation of Black Hole

Black holes are formed when energy is put in a small region of space, I was wondering if there is a threshold to how much energy should I add in a certain volume of space to get a black hole, I read ...
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Relativistic density

In the non-relativistic region of the space, with matter of mass $M$, and volume $V$ the density is given by \begin{equation} \rho=\frac{M}{V} \end{equation} If we encounter an equation, for example, \...
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How to make the weight float on water? [closed]

The height of the cylinder is $3 \text { m }$ and the diameter is $45 \text { cm }$. The cylinder is filled with water. The block is of weight $30\ \text { kg }$ with dimensions $30\text { cm} \times \...
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A question on hydrometer

A constant immersion hydrometer floats vertically in water when the weight of its float is 30 g. When it is made to float in a liquid (miscible in water), the weight of its float is increased by 10 g. ...
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1answer
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Charge distribution and electric field on a conductive sheet

I have a sheet of paper, clad with a half-circle shape of conductive material. The half circle is not filled to the center. The inner radius is about 8cm, and the outer radius about 12cm, not that the ...
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1answer
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Why does the speed of sound decrease with increase in density?

In my book it's written that speed of sound will in increase with increase in density of the medium as molecules with get closer to each other, but after some browsing on internet I found out about ...
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Body submerged in two liquids

A container has 2 immiscible liquid of different densities. Suppose water on botton and kerosene oil on top. A body floats at the boundary of both such that it is partly in water and partly in the oil....
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Magnetic field energy in a coaxial cable

I came up with a conceptual problem when I was doing an exercise which involved calculating magnetic field energy in a coaxial cable. The cable consisted of one inner solid conducting cylinder ...
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Free Fall with Drag and Varying Air Density

I am trying to plot a graph in Excel describing a free fall of an iron sphere dropped from an altitude of 12 km, while taking into account the different levels of air density affecting the drag. The ...
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1answer
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Water at temperature of 4° C [closed]

We know that the density of of water at $4°\rm C$ is maximum $1\rm\: g/cm³$. But how is it possible?? Suppose I have $1kg$ of water at $4°\rm C$ .So it's density is $1\rm\: g/cm³$. But what if the ...
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1answer
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How is the buoyancy force applied when the denser liquid is higher than the less dense one?

Imagine we have to liquids with densities $\rho_2$ and $\rho_1$ and $\rho_2>\rho_1$. Suppose we pour $\rho_1$ into a container. And then we pour $\rho_2$ on it. As a rule, the denser liquid ($\...
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Why the liquids that are denser, place lower than those who have lower density?

can somebody explain Why the liquids that are denser, place lower than those who have a lower density from a macroscopic and microscopic point of view??
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Why is an event horizon dependent on density?

It’s frequently stated in Astronomy documentaries that you could replace the sun with a black hole of equivalent mass and the orbital mechanics will continue as normal. This works fine in dispelling ...
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1answer
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Charge Density as a function of the Electric Field

A ball with radius $R$ has a non-uniform charge density $\rho(r)$. The electric field of the ball as a function of position $E(r)$ is known. How would you then find $\rho(r)$? I was thinking that, by ...
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Accurate method or instrument to measure density of shaving cream foam or whipped cream foam?

I am currently filling a "standard" stainless steel cup of known volume with foam and then I weigh it. Then I calculate density. This method is pretty messy and I have to be careful about how I fill ...
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Question About Buoyant Force and Weight of an Object

Looking at the relationship between buoyant force and the weight of an object, I found this explanation, which makes sense "If the buoyant force is greater than the object's weight, the object ...
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Why do all heavier gases in the atmosphere not settle down to the surface? [duplicate]

Some pollutants heavier than air that are released into the atmosphere include $\text{CO}_2,\text{SO}_2,\text{SO}_3,\text{NO}_2$ etc. Since these gases are heavier than air, Why do they not settle ...
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How to calculate thermobaric heating and decelleration when object go from space into atmosphere (2D)

I'm making 2D game where ship landing from space to planet. I want to add atmosphere to planets with gradient density depending on height. And I want to use this atmosphere for converting object speed ...
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1answer
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Is it faster to get warmer in warm vapor or in warm liquid?

Is it faster to get warmer in warm water vapor or in warm water in liquid form?
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Would gases of different densities separate in a scuba cylinder?

In scuba diving, we use the following gases: Air - mostly made of N2 and O2 O2 He If I was to fill a cylinder at 230bar and leave it aside, would the gases start to separate at some point due to the ...

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