Spinning Definition and 581 Threads

To amuse my 1.5 yr old granddaughter I tied a 5-foot string to her doll and suspended it from the end of one blade in a ceiling fan. As you would expect, the doll spun in a circle maybe a foot or so lower than the blade. After about 10 minutes, the doll slowly lowered to a point dead...

One simple question: why do liquid mirrors assume a parabolic shape when subject to uniform angular motion? (I mean, why not circular, or some other reasonably curved shape?)

I'm not sure if these are very clear questions, but here goes: 1. If a fairly large nucleus is set spinning, then it should generate a small magnetic dipole, right? I'm wondering, how would you calculate it's magnetic moment, using the properties of that particular nuclide (e.g. mass, charge...

when talking about conservation of angular momentum of a spinning ice skater, the contact surfaces are assumed to be frictionless. why?

Hello again all. This is my 6th posting requesting some assistance for some new physics problem. It is getting a bit easier to understand but I would like some review and comments on the following problems. My answers are marked with an astericks. You do not have to necessarily provide me...

Why does the point singularity of a black hole turn into a ring if the BH is spinning? What would the singularity look like if the BH were spinning on 2 axes? (What if the BH were really a multi-dimensional construct and were spinning on more axes?) What is the volume of a ring singularity...

why do bottles or any other things thrown up with a twist always spin about their centre of gravity? Also if all forces pass through centre of gravity of a rocket in space, it will not rotate , even though there is a net moment about any other point except the cg. why

hie everybody, this is my first post on this interesting site... :biggrin: i am not sure how do i count the amount of force needed to turn such a pulley from the spindle attached to the dowel through the spindle. the pulleys are fixed to the dowel and are not movable. they just turn as the...

For example, there is a rotating cylinder with a moment of intertia of 1.5, a speed of 10 rad/sec and a force perpendicular to the rim of 5 Newtons and they have a kinetic friction coeffecient of .5. How long does it take to stop?

Hi there, I have little physics knowledge, just a few poorly understood concepts that I have overheard. Something has been on my mind recently and I though maybe your expertise could assist? There is a theory that says something about the spin on a particle only being determined when a...

ill explain how it works: two cilinders are counter rotative now ill explain what it does one of them represented by a cigarete or similar take the cigarete by the center with the filter aiming at 9 oclock, spin it holding it by the center till the filter points at 3 oclock (going...

A rectangular piece of paper spins rapidly about its longitudinal axis as it falls through the air.It takes longer to reach the ground than other shapes of paper.Why is this given that it spends a lot of time edge on to the flow of air and so encounters less resistance from the air than a...

Hi All! This is my first real post here. I have a pretty basic question regarding rotating objects and the manner in which the rotation becomes a translation. If I drop a bicycle wheel against the ground, it bounces back toward my hand. But if the wheel is spinning as it falls, it will...

A pion decays into two photons with coupled (opposite) polarizations, one of which passes into a black hole spinning clockwise relative to an observer,and the other passes into a second black hole also spinning clockwise relative to the same observer.After a long period of time the photons...

A person stadns on a platform, initially at rest, that can rotate freely without friction. The moment of inertia of the person plus the platform is I_p. The person holds a spinning bicycle wheel with axis horizontal. The wheel has momemnt of inertia I_w and angular velocity \omega_w. What will...

Does a rappidly spinning mass experience an effect in GR that is equivalent to mass dilation in SR? I so, would it have a stronger gravitational field than at rest?

Gravitons increase the speed at which a charge sphere spins and increase its mass. So an electron has a smaller mass than a proton because its spins more slowly. Because the proton has 1835 x mass of electron and because the electron spins at 10 ^ 14 metres per second - to give the observed...

Hello, I am working on a project involving static electricity. I am trying to build a motor type device that can accumulate a static charge through two disks made of dissimilar materials (I’m still working out which two materials would be best) spinning past each other in close proximity. I’m...

how does the Earth keep spining on its axis? is it because it still has the energy it gained when it was formed because it doesn't lose energy into space cause there's no particles out there, but then i was thinking does it loes any energy through IR radiation? just curious.

I read somewhere that a spinning mass with no charge creates a mass version of a magnetic field.Is this true?

Ok, I'm using Beer and Johnston's engineering Mechanics/Dynamics book for class, and i don't particularly enjoy it's lack of explanation for the following problem: The graphic shows a bullet flying to the right with the x coordinate pointing along its long axis and the y-axis perpendicular...

I was wondering me why a bullet is shoot spinning around it axis of symmetry. The cannon of the gun has usually small channels in spiral shaped, to exert a torque on the bullet in order it can rotate about it axis (i suppose). I've been thinking about this, and i heard that it has to do with...

I'm trying to calculate the angular momentum of a coin spinning about a vertical diameter about its center of mass. Given is mass, diameter, and angular velocity. I thought it would be L=\frac{1}{4}MR^2\omega. The angular momentum about a point away from the coin I thought would be...

The linear velocity of rotation of a spinning ball of the gravitational field matter (gfm) is faster at its edge than in its central part. According to Einstein's theory of the spinning disk, the spacetime curvature at the edge of the gfm ball is larger than that in the central part; and...

I heard about a technique where mercury or some other liquid is spun in a dish until it assumes a parabolic shape. Would this work in space? Could a flat membrane of liquid metal do just as well? It could be liquified by an electric current and start out flat like soapy water in a bubble wand...

What is the angular momentum of a spinning solid sphere of mass 'm', equitorial velocity 'v', and radius 'r'? (The mass of the sphere being uniformly distributed and the spin being along a single axis only) I can't figure this out because the common textbook formula for angular momentum...

Wheels and Crazy Spinning Things! For the illustration of the following model, go to http://www.corniceventures.com/images/wheels.JPG If the 2 wheels ("B1" and "B2") are the same diameter (40 inches) and are rolling forward at 4 miles per hour...Would belts "D1" and "D2" rotate hubs "C1"...

My heads spinning help! As usual I've left my work to the end of the holiday and after 2 hours of physics questions my head is in a spin... i have a cou[ple of simple quetions where i know the soluion isobvious but i can't get my had around the answers... would anyone be able to point me in the...

First off I will step out and say that Astromomy and Cosmology is not my bag! I am a Computer techie through and through but the other day I was on space.com and saw the coolest thing and was wondering where I can read more on it or if anyone here knew more about it They were talking about a...

Here's the problem and I'm close to the answer, but I guess close isn't good enough on a Physics exam. A spinning solid disk, rotating with angular velocity Wo, is put down on a level surface. It slides and rolls until it reaches an angular velocity W at which it rolls without sliding. Show...

what keeps the Earth spinning? or more exactly, what drives the planets in our solar system to spin and rotate around the sun? what will happen if Earth stop spinning?