Independent variables of the Lagrangian
Why are y and y' treated as independent variables, while they are not? Another slightly related question: if ' = d/dt then df'/dg' = df/dg because f' = df/dg g', but if we differentiate f' to g' we...
View ArticlePhysics Newbie - Newtons 1st Law - Frames of References & Observers
Hi All Let me start by saying that I am new to this forum and I am new to physics. I've always had an interest in getting an entry level understanding of Newton's Laws of Motion. I also apologize if...
View Articledevelopment of mechanics of a rocking problem
Hi I want to develop mechanics of a problem which is as follows. Suppose there is an inverted glass (cylinder) lying on a table. Now suppose there is a mass (or coin) on the top of glass. If we provide...
View ArticleEnergy of charge distributions,advantage of one equation vs the other?
here are the two equations i'm dealing with: Eq. 1: $$W=\frac{1}{2}\sum_{i=1}^n q_{i}V(r_{i})$$ Eq. 2: $$W=\frac{ε_{0}}{2}\int{E^{2}dT}$$ both equations describe the energy required to assemble a...
View Articlephotobleaching of fluorophores
Can someone explain the cause behind photobleaching (http://en.wikipedia.org/wiki/Photobleaching) of fluorophores when they are continuously excited. The wikipedia article does not really explain why...
View ArticleUnderstanding derivation of scattering from Maxwells eqns...
I am trying to follow a Maxwell's equations derivation for light scattering but don't understand 'why' the authors do the steps they do at this start bit. Help would be greatly appreciated... It starts...
View ArticleHeat transfer through an insulated steel wall due to hydrocarbon fire
Afternoon all, I am interested to hear any and all suggestions as to how one would go about modelling the rise in temperature on the "safe" side of a wall, after a given time period over which the...
View ArticleWhat is the advantage of Hamilton's canonical equations?
Hi! I would like to know that in what circumstances Hamilton's canonical equations are superior to the Lagrange-equations of the second kind. We know that every second order equation can be rewritten...
View ArticleCreating nanoemulsions by means of Electrospray
Hi everyone, I have recently been trying to make a nanoemulsion of an aqueous solution by means of Electrospray. The basic principle is supplying a fluid through a very thin capillary tube and applying...
View ArticleNoether's Theorem For Functionals of Several Variables
My question is on using a form of the single variable Noether's theorem to remember the multiple variable version. Noether's theorem, for functionals of a single independent variable, can be translated...
View ArticleElectron Gravity Question
Has anyone ever "fired" an electron down the center of an evacuated tube (horizontally) to see if the electron follows the same trajectory as a bullet fired from a gun? This might seem like a...
View ArticleElectric field due to a charged particle at a random point in space
Can we calculate the electric field at any given point in space even if there are no charged particles there? The equation for electric field given in a standard EM course is kqq0/q0r^2 where q0 is a...
View ArticleFree energy changes in a canonical ensemble
I have a question that has puzzled me during the last couple of days. Suppose that there is a system (e.g. a small box filled with gas) that is connected to a heat bath (much larger than the system) at...
View ArticleExternal electro-magneteic field acting on a wire
Hello, I am interested in knowing what happens ta wire trough which current is flowing, when an external magnetic, electrical or both , field is applied? Does the voltage or current change, can it be...
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2D heat conduction of layered composite model
Hi, I am trying to formulate a 2D model to calculate the temperature change over time in a composite material. The material consists of several layers, and is heated from all edges by a known...
View ArticleFluid Dynamics
Hey guys, I've been wracking my brain for a while, and thus I have landed here yet again. My problem is the following: Say you have a pipeline with a venturi injector, and intermittently a large tank...
View ArticleLinear Velocity
Good afternoon, I am making way through this paper and I am having trouble "seeing" how the linear velocity AE is derived at the top of http://articles.adsabs.harvard.edu/c...IF&classic=YES Any...
View Articlerealization we are moving in a system
Hello, I am having one question about whether we can realize we are moving in a system, or we think that everything around us is moving away from us. This question popped up while I was thinking about...
View Articlesolutions to laplace's equation & uniqueness thrm #2 (Griffiths)
In griffith's intro to electrodynamics (4rth edition), ch. 3, pg. 121. here is the second uniqueness thrm for the solutions to laplace's equation: Quote: Second uniqueness thrm: In a volume V...
View ArticleClassical statistical mechanics. Phase space.
For any ensemble ##dw=f(p,q,t)\frac{dp dq}{h^{3N}N!}## I do not understand this definition. ##f## is probability distribution function. What is ##dw##? This is probability of finding phase point in...
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