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"Stress" around fulcrum
helo, I have a couple of forces described in f''(t), and the f'(t) yields a momentum vector plane like pic: in this picture, we have a solid square plate of some hard material, and an axis where the...
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Calculating Induced EMF in Moving Wire
In the classic problem of the induced EMF in a moving conductor (as in the picture above), the calculation for the induced EMF is as follows...
View ArticleBarrel roll with/without slipping
Hi guys, I'm wondering if I roll a barrel which rolls without slipping down an inclined plane vs. a barrel which only slips down the plane - who will get down faster and how can I show it...
View ArticleIndex of refraction and density
Hi, Is it possible that the medium of lesser density has larger index of refraction? If yes, please give me some examples. Thanks in advance.
View ArticleConverting energy to impulse
Problem: A nuclear generator produces energy used to accelerate a rocket. Given energy and mass, what is the acceleration a? Nuclear generators produce energy in GeV or joules which have the dimensions...
View ArticleElectric field from a charged disk
This is rather strange and has been bugging me, from chapter 22 (Electric fields) of Resnick & Halliday: So suppose you have a charged disk of radius ##R## (the disk has no thickness and charge is...
View ArticleDo Voltage/Temperature measure Energy; Fields/Pressure measure Force?
Would it be correct to call Voltage and Temperature intensive measures of Energy, and call Electric Field and Pressure intensive measures of the potential for Force generation? If so, is Voltage...
View ArticleHow are Entropy and Temperature conjugate variables?
Can someone conceptually explain to me how Temperature and Entropy are conjugate variables? I would imagine that Temperature and Internal Energy would be more appropriate, as I understand Heat flow...
View ArticleHard-point particle
Hi all, what do you understand by a hard-point gas?, I mean in terms of its hamiltonian. Thanks in advance.
View ArticleDegradation of Steel Due to Punctures
Hello everyone obviously smarter than I. There is an answer I seek, to a project that is willing to be done. I'm considering manufacturing a piece of fitness strengthening equipment that is somewhat...
View ArticleWhere did Newtons Second law come from?
I want to preface this question with the fact that I am a scum noob. How did Newton come up with the second law of motion. As I understand it, it is only derived through experiential observations. I...
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Disk radial change with temperature rise
Hi guys, Heard an interview question from a friend, the guy asked him what happens to a disk with internal radius r and external R such as the following: When heated. He told me the answer is that the...
View ArticleHow does light get absorbed if its a changing electric/mag field?
Hey guys, I was just stuck on this idea. I know that in the classical sense, light or any kind of electromagnetic radiation is a continuously changing electric and magnetic field. As e field changes it...
View Articleelectric monopoles cannot radiate?
According to a physics gre book (Conquering Physics GRE by Kahn &Anderson), electric 'monopoles do not radiate'. They give the example that a uniformly charged sphere can change radius and not...
View ArticleNoether theorem and scaling, ex.: 1-D Harmonic Oscillator
Hello, if I think of the harmonic oscillator action S = ∫L dt, L = 1/2 (dx/dt)^2 - 1/2 x^2, and then of the "scaling transformation" x -> x' = 1/a x (a>0, const), then x = a x', and in new...
View ArticleIncrease moment of inertia, slipping down an incline
Hi, I'm trying to find out what effect an increase in moment of inertia of a cylinder would have on slipping when the cylinder rolls down an incline. Starting with: ma=mgsin(theta)-f, where f is the...
View ArticleIntegrating Newton's law
Hello everyone, What does it mean if I integrate Newton's law of universal gravitation with respect to r. F= GMm/r^2 become 3GMm/r^3 . Is this the work needed to escape a gravitational pull ? Thank you
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Regarding the inductance model
The inductor below is conducting an arbitrary current, with the switch on. Suddenly the switch is set off and and voltage over the inductor raises to the negative infinity according to Vl = L*di/dt...
View ArticleDrift speed of an electron
So in Resnick & Halliday, it explains that the drift speed, or the average speed of charge moving in a wire under the influence of an electric field E is defined by the equation ## J = (ne)v_{d}...
View ArticleElectrical Power Equation Contradiction
We know that the rate at which electrical work is done (electrical power) is defined as: P = I2*R , or: P = V2/R The formula P = V2/R implies that if the resistance of an electrical component (R) (for...
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