Potential energy and kinetic energy
So today in class we were talking about gravity and my professor said that generally KE = -.5PE And so TME = .5PE I don't understand how that works.
View ArticleStatics problem
Hi guys. I have one problem from competition that I can't solve. I'll try to translate it. "rod of mass m and length l is lying on a ball of radius R in state of equilibrium. The rod makes angle θ with...
View ArticleMoment of Inertia of a Disk
I know that the moment of inertia of a disk about the axis perpendicular to the plane of the disk is I=1/2 MR^2 and by the perpendicular axis theorem the moment of inertia about the other axis is I=1/4...
View ArticleWork Resulting From a Magnet
First, this is not a post about perpetual motion machines, although thinking about perpetual motion machines made me think of some issues. Something that is bothering me is the idea of a magnetic force...
View ArticleNeon and polarity measurement
Hi All, I would like to know why the neon lamp is used to measure electrical polarity. What is the working mechanism involved. Best wishes, DaTario
View Articlewhy doesn't a yo-yo come back to its original height?
Does a yo-yo lose all its translational kinetic energy when it reaches the bottom and turns around? It seems at the bottom the string should give the axle of the yo-yo a violent tug, so maybe some of...
View Articlecharge on a balloon
Two new uninflated balloons do not attract or repel each other. But after blowing them up, they repel each other and stick to the wall, without having to be rubbed against hair or anything else. Why do...
View Articlederivatives and equilibrium position of a spring
I determined the equilibrium point of a spring by setting the potential energy function U(r) equal to zero and solving for r. But I just looked at the guided solution, and they took the derivative of...
View ArticleWhat happens to the electrons in a magnet
Suppose I'm holding a magnet and then lift a paperclip(or another magnet) with the magnet. Now the energy density of a magnetic field or the energy that went into making the magnetic field is [tex]W =...
View ArticleFeynmann Sprinkler
Was reading my old copy of Surely You're Joking Mr. Feynman again; ran into the anecdote about the Feynman sprinkler. In the book, one guy argues that the water going into the sprinkler will cause the...
View ArticleCoriolis and Other Effects
I've been trying to understand the Coriolis effect on the Earth's surface. The general equations produce two terms: The first is R'' and the second is 2ΩxV, where R is the position of the point on the...
View Articlex = Asin(wt + angle) and circular motion diagram?
This is the type of diagram I'm talking about: http://www.google.co.uk/url?sa=i&rct...85070490503327 It's the image the image next to Quest 3T If x = Asin(wt) surely the x value is the length of...
View ArticleMomentum of a falling object
Hi. I am studying physics on my own from scratch, so far so good, though I've run into this concept I am struggling to understand. If we push a large rock over a cliff, it falls because of the pull of...
View ArticleBuilding theoretical model for phase seperation
I have three elements, A, B, C, that under certain conditions (rapid heating and cooling) form one ABC phase solid. Sometimes when I add a fourth element, D, I get two phase (AB,CD) solid. Obviously...
View ArticleInternal energy in expansions
I've got a few issues with the topic of thermodynamic expansion, ΔU, etc. With ΔU=q+w, this w is to mean work done on the system (positive contribution to ΔU) minus work done by the system (i.e....
View ArticleBeam Emittance
Hi, I want to write a very simple code to plot the beam emittance knowing x,y,z and vx,vy,vz of each particle. I have generated with a tracking code a very simple beam (cone distribution with 1°...
View ArticleWhy this solution to the 3D periodic Navier-Stokes?
Who can provide a physical understanding to this solution to the 3D periodic Navier-Stokes equation: http://purvanced.wordpress.com?
View ArticleParticle/dipole acceleration in non-uniform magnetic field
I've come across a few places that mention that dipoles and charged particles accelerate in non-uniform magnetic fields. Is this true? If the Magnetic force is always perpendicular to the velocity of a...
View Articleground in electric circuits
The term ground has always confused me. For instance: I have always thought of a battery as a collection of negative charges at the -pole and positive charges at the +pole. But with this picture what...
View ArticleMultiple parallel plate capacitor question.
Consider a capacitor with 4 parallel plates and 3 dielectric insulators arranged like this...+I-I+I- The insulator in the center has an equal amount of + and - charge on each side of it so shouldn't...
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