Angular momentum in a half rotating body
If we look at the classical formula for the conservation of angular momentum, L=mvr, we can easily see that, if the radius of a rotating body is shortened, its velocity must increase in order to...
View ArticleClik here to view.
Sizing a DC motor to move a weight and counterweight
This might be a silly question for some but I was wondering how do I size a DC motor to move a weight and counter weight? Suggestions for a better design are also welcome. I want to build an enclosure...
View ArticleIrregular case of induced EMF
Dear colleagues, My question here refers to the EMF induced in an incomplete ring that is stationary amidst a time dependent magnetic field. We know from Faraday's law that EMF is created upon changing...
View ArticleCan photon capture give electron and positron opposite charge
Is it possible, in theory, that the physical entity electron e(-) and its charged opposite positron e(+) both obtained their respective electric charges by simultaneous capture, by a more fundamental...
View ArticleEM waves and the direction of E-fields & B-Fields
What I'm wondering is whether or not the E-fields and B-fields making up an EM wave always point outwards. Would it be possible to have an EM wave where either the E-fields or B-fields, or both, point...
View ArticleAccelerating reference frame
I'm attempting to build a line follower robot and I'm currently in the process of building appropriate models. For the control system I need to define a coordinate system. The most convinient...
View ArticleUnderstanding the spectrum of frequencies
What is the distinction between EM waves and Sound waves. I know that sound is cyclical vibrations in some sort of medium. When the frequency increases, do these vibrations become EM waves? I know that...
View ArticleWhat makes materials seem colored?
I don't know the reason of materials' color? Why one matter is blue and another is red? Which mechanism is responsible for their color; Absorption, Luminescence, Scattering, Reflection?
View Articlewhy does the kinetic theory of gases neglect potential energy ?
My textbook says that the forces of intermolecular attraction between gas molecules are very weak due to large intermolecular spaces between them , that's why they're negligible , Does this have a...
View ArticleWhat is the mole ?
I've read a lot about the mole , avogadro's no. , molecular mass and such , but I can't seem to understand anything , and no , the wiki article wasn't helpful at all ! Put simply : 1- I read that the...
View ArticleTime taken for magnetic field to permeate a speherical volume
For a stationary plasma of electrical conductivity 1.00 x108 Ω-1 m-1 estimate the time taken for a magnetic field to permeate a spherical volume of 3.0 m radius. I have been looking at the question for...
View ArticleAngular Momentum in a Kepler Orbit
I got myself here a satellite rotating at a large distance around planet X. Distance from center of planet X = 100, mass of the satellite = 1 gram (really small), mass of planet X = 1.0 kg velocity of...
View ArticleDirection of Electron Flow with Real Batteries
Hello all - a quick question that I can't seem to find an answer to online that I trust... While the conventional current model describes flow of positive charges around a circuit, we know that current...
View ArticleThe factors in this system that would generate CEMF
Hi I have a Solenoid(No core) and a small magnet that is stationary in it. The Solenoid is powered off/on. What would cause Counter-EMF if the Solenoid is on/off? Only the motion of the magnet? What...
View ArticleElectromagnetic systems always dissapative?
Imagine a blob of continuous charge in vacuum, the fluid elements will exert a force on each other and thus radiate away energy to infinity and thus be forever lost, does this mean that charged...
View Articleenthalpy is null at zero K ?
Hello world ! i have a 'simple' question : enthalpy is null at zero K for all materials ? I think yes, but i don't know how can i show/explain this... can you help me please, i want to understand this...
View ArticleElectrostatics in RC\DC Circuits-feedback process
Hello, I've always had problems conceptualizing the physics behind circuits, and it always felt like information is hidden from me. Lately I've been trying to analyze circuits in the microscopic and...
View ArticleRotational Kinetic Energy of Body in another body reference frame
I have two rigid bodies floating in space that are kinematically constrained by a joint (think of a 2 dof link mechanism floating in space). I have a body fixed reference frame on each rigid body plus...
View ArticleLongitudinal Wave Equation meaning and derivation
Hi, I have recently been studying waves, and I understand the transversal wave formula y=Asin(w(t-x/v)) which gives the y coordinate of a point at x along the x-axis in the instant t. However,...
View ArticlePassengers in a falling plane, author request
I'm an author and I want to correctly portray a scene (with a bit of artistic license) in my next book. However, I don't think I understand the physics of the situation. Scenario: Passengers flying in...
View Article