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

learn more… | top users | synonyms

0
votes
1answer
519 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?
0
votes
1answer
199 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 ...
0
votes
0answers
29 views

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 ...
0
votes
0answers
144 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 ...
0
votes
0answers
73 views

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( ...
0
votes
0answers
30 views

Electromagnetic Energy and Momentum

I'm trying to show that the electromagnetic energy density and momentum density satisfy the inequality: $ u \geq c |\vec{\wp}| $, where $\wp$ is the momentum density and $u$ is the energy density. I ...
0
votes
0answers
79 views

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 ...
0
votes
0answers
65 views

Stress and Mass Density Distribution

I'm simulating electromigration in a copper wire using COMSOL and trying to see the back-stress caused by material transport. However, I do not see any stress growth. In other words, the atomic ...
0
votes
1answer
223 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 ...
-1
votes
2answers
176 views

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?
-1
votes
0answers
13 views

Spherical charge distribution along a wire of length $L$ in which its center coincides with the origin of the system

I've already tried to find the expression but I don't find the expected result for the quantity of charge when I use the expression I found. For example, I checked it by integrating the expression ...
-1
votes
1answer
86 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 ...
-2
votes
1answer
191 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?
-2
votes
2answers
90 views

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 ...
-2
votes
1answer
404 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 ...
-4
votes
2answers
98 views

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 ...