Hamilton-Jacobi equation in spherical coordinates
I was looking at the Wikipedia entry on the Hamilton-Jacobi equation, and was confounded by the equation at the beginning of the section on spherical coordinates:...
View ArticleClassical Rational Reasoning
(1) The year 1900. (2) Plank made the crucial discovery, the fundamental law of existence: (3) [itex]\Delta E = h \cdot \nu [/itex] (4) In the same year, Henry Poincare derived the equation (5) [itex]E...
View ArticleIs gas pressure caused by the weight of the gas above?
I have two closely-related questions, which are probably just one question: 1. On the National Weather Service website (http://www.srh.noaa.gov/jetstream/at...weight.htm),it says "When we measure air...
View ArticleGauss law and electric current
According to the Gauss law, the extra charges gather on the surface of a conductor. When there is a current in a conducting wire, do the charges only move on the surface of the wire or we have current...
View ArticleForces in Damped Forced Oscillations?
The example I'm thinking of is a mass spring system. x = Ae^([itex]\gamma[/itex]/2)t cos(wt +a) + Ccos(wt) If the steady state has been reached, the displacement due to the free oscillations will be...
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Peaks at reflectance graph
Hi all When one measures the reflectance of say silicon, certain peaks appear in the graph. I am wondering, if anyone can explain the location of the peaks and their meaning. Here the graph is, I hope...
View ArticleStern Gerlach Experiment
I'm confused.So a dipole needs a nonuniform field for the net force to not equal zero, cool. My question is how do they go from F = -∇(μ * B) = ((μ_z)(dB/dz))*(z unit vector) how come the gradient has...
View Articlewhat affects heat transfer within a material?
so i'm told that temperature difference is ultimately what results in heat transfer. But when considering what happens inside a uniform material, if temperature difference was solely responsible for...
View ArticleIs this abstract clear?
Hello, Is the line of thought clear to you when you read the text below or do you find parts where you get lost or even see something that sounds wrong? Title: Energy transfer between point particles...
View ArticleBuoyancy and gravitation
Imagine you are in an elevator accelerating downwards with acceleration g, holding a balloon (which would fly upwards if left outside). Now if the thread you are holding snaps, what will happen to the...
View ArticleCar flipping over another car
Hi gurus I am not physics but I would like to know the following car A jeep Grand C car B Jeep Liberty is it possible for car A to flip over car B if A hit B at 45-50 MPH. in a dry road condition ?...
View ArticleElectrical conversion
How can I get an AC voltage from a 12volts battery supply? Please help me out.
View ArticleForce, velocity and linear momentum
If we can connect the torque τ with the velocity precession Ω and angular momentum L, as: τ = Ω L. So, analogouslly, exist a equation that connect the force F, the linear momentum P and with some...
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Electric field of a point charge in uniform motion
In Griffiths Chapter 12, pg 527: Suppose a point charge is moving along x, we obtain the following E-fields: Questions 1. Is the vector R solely in the x-y plane? 2. What happened to the coordinate 'z'...
View Articlepolytropic process vs perfect gas eq
The polytropic law states: (1) P1V1n = P2V2n The perfect gas equation states: PV = mRT --> P1V1/T1 = P2/V2/T2 If T1 = T2 then (2) P1V1 = P2V2 So, how can equation 1 and 2 both be true for the same...
View Articlethermodynamics: deriving the quantum volume
so we used an equation in class to basically describe the relationship between some quantities of a vibrating string held fixed at both ends. and i noticed (just now...) that this was.. well.. i don't...
View ArticleRijke tube: Why Sound is maximum when heated 1/4th length from bottom
Why is it that the maximum sound coming from a Rijke tube happens only when heated wire gauze is placed at 1/4th the length of the tube from the bottom. According to Rayleighs criterion(copy pasted)...
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Lenz's law: determining current direction
I a can't seem to find out how to determine the direction the current will flow in... I would really appreciate an explanation. Thanks!
View ArticleHeat Transfer Problem
Suppose you have a cylindrical rocket engine with surface temperature T and you want to measure temperature on the inner wall T0 of the combustion chamber (assume 1 dimensional heat transfer). The...
View ArticleHomemade Particle Accelerator?
Hi PF, I've been looking to do a physics project for a while, and I thought about trying to build a particle accelerator at home. I know there's a lot of potential risks involved, and I imagine some...
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