Diffusion Definition and 476 Threads

Hi, I'd like to figure out the amount of heat lost in the kinematic action of putting your foot on the ground while walking. I'm not interested in the diffussion of body heat through the shoe or anything, just the heat energy released by the impact itself. I know this is obscure, and probably...

Hello every body I have previously post my question in this topic: Physics Help and Math Help - Physics Forums > Science Education > Homework & Coursework Questions > Other Sciences > Fick and Cottrell Law And after Goku suggestion I post my question here. So my problem deal with the...

Hi all, I'm abit confused about diffusion - I can't seem to understand how to translate the question at hand to equation (from there it is only math...). I have a box with a gas at concentration n0 in it, which is divided from the rest of the box where you have vacuum (for simplicity, the...

hi i have been trying to solve the diffusion equation using separation of variables. i know the answer should turn out something like the normal probability density function but its just turns into a mess when i try it. i am given the following information: \frac{\partial p}{\partial...

Basically the steady-state diffusion equation can be written in a form \nabla^2\phi\,+\,k^2\phi\,=\,S When S = 0, this is just the Helmholtz equation - http://mathworld.wolfram.com/HelmholtzDifferentialEquation.html See also -...

Hi. I want to know what's the difference between scatter and diffusion... I am trying to understand what happens to the electromagnetic wave when we are talking about scattering and about light diffusion.. I think that the result of scattering it to make the light to diffuse.. Is that right?

Hey there I was wondering if someone maybe be able to help me with a couple of questions I have. I attach a set of equations the help define the heat diffusion throughout a sphere could you please tell me; in V=rT What is V when r is the radius of the sphere and T is the temperature ...

I have managed to create a simple CFD model to integrate in 3D the heat/diffusion equation, namely dT/dt = k d2T/dx2. This works fine, but I would now like to add the effect of 'less dense rising' assuming the gas is operating in air -- I think I'm right in saying that's called buoyancy (I'm...

Hi, I'm not understanding an example in my book. Can someone please shed some light on it? > Derive the equation satisfied by the temperature u\left( {\mathop r\limits^ \to ,t} \right) at time t for a material of uniform conductivity k, specific heat capacity s and density \rho . Express the...

This phenomina I really don't undertsand. I know that a difference in 2 pressures will cause a force through P= F/A, but what I want to know is, what is type of force of it, what's going on, on the quantum level?

Can somebody give me for mind refreshment the differences between those process : diffraction diffusion effusion ?

i know that the molecules in the "freedom" form that have charges equal 0. but i wonder why the molecules still moving to create the diffusion and the effusion? some one please explain to me. thanks:!)

I have a question of the form, "how did they go from this step to that step?" I am following a paper from R. Kubo, called "The fluctuation-dissipation theorem". I suspect variable substitution and a simple assumption are used, but I don't know how. Here is the basic expression from which...

I have calculated the coefficient of diffusion of H2 into Air and He into Air as Hirschfelder do so based on Lennard Jones Potential in his book about "Molecular Theory of Gases and Liquids". My figures are: D_{H_2-Air}=7,78 \cdot 10^{-5} m^2/s D_{He-Air}=7,17 \cdot 10^{-5} m^2/s both...

http://arxiv.org/abs/astro-ph/0506364 Title: Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model Authors: Juan F. Lara Comments: accepted for publication in Physical Review D This article presents an original code for Big Bang Nucleosynthesis in a baryon...

Describe the process of simulating a brownian motion with drift of 4 units and diffusion of 2 units. write a program in any application to imulate such a brownian motion. Anyone knows where should i start first if i use excel to do it. I don't know what equation to use.

I am doing research with a professor and he asked me to graph some solutions to a 1D diffusion equations of the following form: C_e \frac{\partial T_e}{\partial t}=\frac{\partial}{\partial z}\left( \kappa \frac{\partial T_e}{\partial z} \right) - g(T_e-T_i)+\alpha (1-R)If(t)\exp (-\alpha z)...

Hello all, I need to know the rate at which Helium will diffuse through a solid, specifically silicon. Assume I accelerate and implant a He+ ion into a bulk silicon substrate. How long will it take to diffuse out of the silicon? I know it will depend on the temp of Si and the depth of...

Hello, I've a fysical problem. A small container (about 10x10x15cm) has a source which releases hydrogen at a small rate. The container has an small oppening 30mm^2. The question is how fast does the hydrogen diffuse to the outside of the container. I've made simmulation (see...

what makes the particles move from a high concentration to a lower concentration?

HELP! A cylindrical metal wire of cross sectional area A = 1 mm2 and length, L = 1 cm, is composed of a material with electron density N = 1029/m3. As a result of scattering, it has a mean free time of ƒä torque = 3 ¡Ñ 10-12 sec. Describe the motion of electrons and the resulting current...

Hand-to-Hand Model for Tropomyosin Fast Diffusion. Semiconductor Mechanism for Diffusion of Tightly-Binding Proteins: http://actomyosin.narod.ru/h2h-model.htm Would you be so kind as to recommend me some expert who could be interested in view a possible semiconductor mechanism for...

The concept of diffusion is confusing me, as it seems to contradict gravity. x = particles of matter with a mass of 1 | = a barrier particle x can permeate Situation A: xxxxx|x (1)In my biology class, we're told, and do experiments to prove that, in this situation, the result will...

[SOLVED] self diffusion of water Hi, I was wondering if anyone could give me a hand- or point in the right direction about a question I have concerning the self diffusion coefficients of HDO vs H2O18. To calculate the effective diffusion coefficients of isotopes of water in groundwater most...

Hello, In a biological course in the university, I asked my professor Which force governs diffusion and He didn't know. Note that i don't mean Fick's first or second law, Einstein's law of diffusion, the Brownian Motion and not even the The Second Law of Thermodynamics, simply what "compels"...

[SOLVED] Which force governs diffusion? Hello, In a biological course in the university, I asked my professor which force governs diffusion and He didn't know. Note that i don't mean Fick's first or second law, Einstein's law of diffusion, the Brownian Motion and not even the The Second Law...