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Is there water flow against gravity?
Hi all, I have been with this issue for some time and think I reached a conclusion but am not sure and was hoping that you guys could help me out with this. I was considering the scenario where you...
View ArticleWrong prove in textbook of optics?
In textbook on optics by Pedrotti (and I think Fowles does the same) on page 493 it is said that: kr=krr=ktr from which follows (k-kr)r=(k-kt)r=(kr-kt)r=0, where k, kr and kt are wave vectors of...
View ArticleNMR net magnetic moment
Let M be the magnetic moment of a system. Below are the Bloch equations, including the relaxation terms. [tex] dM_x/dt=({\bf M} \times \gamma {\bf H_0})_x-M_x/T_2 [/tex] [tex] dM_y/dt=({\bf M} \times...
View ArticleParticle accelerator
I am looking to making a particle accelerator but I don't understand how to make a vacuums. Wouldn't sucking out all the air make the pressure inside very extreme crushing the container? Also how would...
View ArticleSome confusion about balanced forces..
Hi, My question is: 1)When an object falls to the ground, shouldn't the ground exert a force greater than the weight of the object to stop its motion altogether? Because if the forces experienced by...
View ArticleVariables of the double inverted pendulum
I am trying to model the following in a computer simulation: The Acrobot However I am struggling to understand which variables stand for which. In particular, the variables not defined are:d1 and d2...
View ArticlePerpendicular force calculated from torque and point of application?
I hope I managed to post my question the right place! I have a body consisting of a bunch of mass-points in ℝ[itex]^{3}[/itex], and when torque is applied to this body, I'm interested in finding the...
View ArticleMoving Charges and Magnetic Moments
Does any moving charge generate a magnetic moment? I thought so because a moving charge generates a magnetic field.
View ArticlePinball Physics, LIVE CATCH
Hi guys, I'm trying to formalize the physics behind a real life phenomenon that happens in pinball, live catch: http://www.youtube.com/watch?v=E7oGcghhkek This video is not the best example, when you...
View ArticleEstimate of photons/electron/cycle for radio antenna?
Should it be straightforward to estimate the number of radio wavelength photons emitted per electron per cycle (or is it number of electron cycles per photon) of a half wavelength radio antenna running...
View ArticleFinding Spectral Illuminance from total Illuminance
I'm trying to find the "Spectral" Illuminance (lux/nm) of a LED in order to find the spectral irradiance (watt/nm). I am somewhat new to optics, especially when it comes to the radiometric and...
View ArticleHow can Simple Harmonic Motion have angular frequency?
It isn't making any intuitive sense. If it isn't moving in circular motion, how can it have angular frequency or speed? Also, [tex]v=\pm ω\sqrt { A^{ 2 }-x^{ 2 } }[/tex] only applies to SHM with...
View Articlemagnetic field calculation
i'm working on a project and in one of it's steps i need to calculate the magnetic field outside a finite solenoid and i'm stuck there is there any equation to calculate the magnetic field vector in 3D...
View ArticleEntropy and Internal Energy in Fermi-Dirac statistics
What are the formulas for entropy and internal energy in Fermi-Dirac statistics, and how do I derive them?
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Filters for Real World Accelerations
Hi, I'm having trouble with the application of filtering to real acceleration data. I have looked at a lot of recommendations, filtering through fft, butterworth high and low pass filters, and I'm not...
View ArticleWhy is it not possible to derive Cv from equation of state?
Assume you have no knowledge about the microscopic information, all you know about the system of pure material is it's equation of state and number of particles. Why can't we get Cv=(∂U/∂T)V from...
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Charges separated situation
So I have a situation with two charges separated and they make equal angles with respect to the vertical, and they are separated a distance. They have the same mass, and the question is if the charges...
View ArticleWill an oscillating magnetic field penetrate a stainless steel tube?
I am a chemical engineer, not a physicist, so I am a bit rusty on my electromagnetics. I need to set up a fluctuating magnetic field inside of a stainless steel tube (hopefully using a pair of...
View ArticleFluid velocity vs pressure in taper.
I have been running this question through my mind. If you apply pressure to a fluid (with say a piston) through a straight hole then the faster you push it through with applied pressure then the more...
View ArticleIsothermal Expansion of Water/Moving Boundary
Hello all, I've been wondering how water reacts in a closed, rigid system with one moving boundary. Assuming the system is perfectly filled with water, and one side of the boundary moves (increasing...
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