Spinning Definition and 581 Threads

Homework Statement A uniform thin circular rubber band of mass M and spring constant k has an original radius R. Now it is tossed into the air. Assume it remains circular when stabilized in air and rotates at angular speed ω about its center uniformly. Derive an expression for the new radius...

Look at this email I received from a company called ;Wisegeek' they send out interesting news items each day .. "If you spin a clean, new Lincoln penny, it will fall tails-side up about eight times out of 10. Forget what you know about statistical probability. If Persi Diaconis and researchers...

Consider the case where a basketball rotating about its center of mass strikes a wall head-on. The velocity given it parallel to the wall due to the spin is caused by the friction between the wall and the ball as the ball is sliding against the wall during the collision. Friction is proportional...

Homework Statement Find the magnetic dipole moment of a spinning sphere of voltage ##V## and radius ##R## with angular frequency ##\omega##. Homework EquationsThe Attempt at a Solution To find the dipole moment, we need to do ##I \int d \vec{a}##, which would be ##I 4 \pi R^2 \hat{r}##, but I...

So imagine you have two disks, and from your perspective one is spinning on its vertical axis and the other one is spinning on its horizontal axis. What do you call that? And what would it mean to "spin at the opposite polarity" if such a sentence makes any sense at all? Thank you! Sorry if...

Hi All, I've been reading up on hybrid vehicles and how the Honda Insight has an electric motor attached directly to the gas engine driveshaft. Their combined output causes the wheels to spin. My question is in regards to when the electric motor is off but the gas engine is on. Why doesn't the...

Homework Statement We consider a sphere of radius R which carries a uniform surface charge density \sigma and spins with angular velocity \omega around a diameter. We use spherical coordinates (r, \theta, \phi) with origin at the centre of the sphere and the z-axis along the rotation axis...

Homework Statement A rock initially at rest in a sling of length r meters is brought to a speed of n rotations per second after three complete revolutions. It is then released , leaving the sling at an angle of θ above horizontal. When the rock is released, write the initial velocity and...

A discussion with some friends: Suppose you have a large wheel, say 10 meters in diameter and a bell jar with a good vacuum inside, the wheel is rotating horizontally to Earth. In the jar is a bob, and it is on a 10 meter string which is connected to the center of the bell jar furthest from...

When a wheel spins does it generate lift or something, the wheel spins so that the torque force is downwards. for example you measure the weight of the wheel and then you spin then wheel does anything change? The wheel is solid and if their change something does it matter if it is a constant...

What is the moment of the wheel. Dimensions: r= 1 m h= 5 cm m= 1000kg a = 4120 rad/s2 I used the formula T = I * a The moment of inertia can be calculate by Iz =(1/2)mr2or Ix=Iy= (m/12)* 3r2 +h2) wich one do i need to use?

Homework Statement A child is at a playground, and chooses to try the spinning disc (see figure). The radius of the disc is 2.00 m, and the coefficient of static friction between child-surface and disc-surface is μs = 0.350. In the following questions, you must provide algebraic equations as...

I know that time dilation effects everything that moves in relation to everything else that's around the thing that moving. Does that also include vibrating and spinning thing and if it does how so?

Homework Statement A 12.0-kg mass, fastened to the end of an aluminum wire with an unstretched length of 0.70 m, is whirled in a vertical circle with a constant angular speed of 120 rev>min. The cross-sectional area of the wire is 0.014 cm2. Calculate the elongation of the wire when the mass is...

I am hanging an indoor swing. The swing hangs from ropes and the ropes are attached to a single chain hooked into the ceiling. I want the swing to "swing back and forth" but I do not want the swing to "spin" around -- I want it to face in one direction. Is there something I can do to stop the...

I'm trying to understand the relativistically spinning disk within the framework of SR (if that is even possible). I thought to first simplify the problem by considering a spinning ring/annulus, but I don't know if my analysis is correct. I imagined a spinning ring of radius R, spinning at an...

Apologies for a possibly very basic question. I was recently asked by someone to explain to them the answer to the following classical mechanics (uniform circular motion) problem: Consider two discs of different radii, attached to one another such that they are concentric, and each containing a...

As far as I understand it, a nebula initially tends to have a small amount of rotation (on average) and then as it collapses under its own gravity this rotation increases significantly due to conservation of angular momentum (assuming that there is no external torque,right?!). What I'm unsure...

Homework Statement The water stays in the bucket, even at the top of the circular path, as long as the speed exceeds a certain value. Explain why. I think i have a good answer, but not 100% sure. My answer: There is a centripetal force acting on the bucket and the water since they are...

The angular momentum is related to the rotation. And when a black hole has angular momentum, it is said that it is a "rotating black hole". But what does it mean? A black hole does not have a conventional surface, like a basketball. How should we interpret that angular momentum? I asked this...

It's a random thought I had. Let's say you have a single perfect permanent magnet. There is just one magnetic domain, and the magnet is cut so that its magnetic moment is along a single crystal axis. For example, we can imagine a cube shaped magnet, with the magnetic moment pointing straight...

So basically, I was doing my AP Physics 1 homework and came across the spinning ice skater question yet again. The question states, "An ice skater is spinning about a vertical axis with arms fully extended. If the arms are pulled in closer to the body, in which of the following ways are the...

So I have heard that the Earth is spinning away from the sun at a slow rate. Is this rate fast enough to negate global warming by a significant amount, or is it too insignificant to effect anything?

So I was thinking about something quickly in science while my Science teacher told me about electromagnets creating electricity and stuff. Then I thought, what if there was 2 big magnets both negative together creating friction in the middle?(idk) Then a nice big pole which transfers Friction...

suppose a platform "P" is rotating about the z-axis wrt x-axis . another platform "Q" rotating about z-axis below "P" with same angular velocity wrt x-axis standing on Q , P is at rest wrt Q, After some time rotational inertia of P about z-axis starts changing with time standing on Q , P will...

Would the gravity of Earth decrease if the Earth stop spinning? Would the gravity be affected at all? Does the gravity of other orbiting bodies cause the Earth to speed up its rotation and slow down its rotation during the year? thanks.

I have an electric fan that looks like this: Recently, when I flip the switch, the fan blades won't start spinning without any initial assistance. I have to manually push the blades to get them going. But this is not due to too much friction, the friction is the same. When I flip the switch...

Ok, so here's the deal. I'm working on something that I SHOULD know the equations for after 5 years of school and a degree in mechanical engineering, but then again I can't remember why I walked into a room most times. So if ya'll could give me some guidance and at least a starting point I...

I was wondering it the projection of the measurement axes onto a spinning vector modeled by a plane would produce correlations of entangled particles in line with what is found by experiment. Does anyone know of any discussions on this subject? Would this lead to stronger correlations than spin...

Homework Statement A particle is fixed to the edge of a disc of negligible mass making an angle θ0 with the ground in a uniform gravitational field, and is free to rotate about the center of the disc. I need to find the equations of motion. Homework Equations The definition of the Lagrangian...

Hi, If we apply a torque to a spinning wheel such that the torque vector lies in the plane of the wheel, it will precede around the axis perpendicular to the angular momentum and the torque. What happens if the wheel is mounted such that rotation around this axis is absolutely impossible and...

Sorry if this question has already been addressed. I know that, at least for a point mass or a rigid body traveling at constant velocity, in special relativity kinetic energy T is defined as: T = E - Mc2 where E is the body's total energy and M its invariant mass. I have a problem in...

I want to be able to tip a can by building a device that fits inside the can and is able to tip it even when the can is completely closed. I have a motor and an arduino to control it. Would I be able to tip it by spinning a weight around the vertical axis of the can? Or would action and...

In our class we were playing with a toroid shaped object made of foam (Probably). While tossing it around, not only was the disc rotating simply. It was well, sort of vibrating. Like one end of the object is up and the other is down then after a small interval the vice versa occurs. What is the...

The Earth's rotation acts as a clock and defines a rather precise unit of time called the day. We could go out in outer space and spin a marble and get a reasonable clock. On the other hand, it is my understanding that you can't do this with an electron, that is, you can't start an electron...

So, I am watching this show about airline crashes and apparently, a A380 has gone down because the speed limiter on a spinning engine rotor broke, and the part spun so fast its ultimate yield strength was reached and the material shatterted. Thats got to be one really fast spinning rotor! But...

Ok I heard that a very fast spinning top, in a perfect vacuum, on Earth, would stay spinning forever, and I suppose it would in the middle of the vacuum without falling, because spinning at lightspeed means it can't move 1 down, so if the speed in this top stays in it, then it could avoid...

Why does the Earth not fall into the sun? Is it because Earth has angular momentum? or is it because the Earth has orbital momentum?

Hey guys, this is not really a h/w question but I thought this would be the best place to get a relevant answer. So I was doing physics h/w last night and found that I could spin on my chair (a standard office swivel chair) by moving my arms in the opposite direction to the way I wanted to...

Homework Statement A wheel spins in outer space, it is in the shape of a ring (negligible thickness) with a radius of 1 meter and a mass of 1 kilogram, it is spining at π Radian/sec around its central axis (z-axis) in a fashion that is like any other car wheel. Just then, an impulse of 10N*sec...

Hello all- This is a logistics question asking for some guidance, rather than one requiring scientific explanation. I'm currently in a battle of sorts with a friend to record the longest spinning ring possible (like a wedding ring). Basically, spin the ring on a table and time it until it...

Hi, I'm having a discussion with someone on the plausibility of the physics in a science fiction movie (I know, very efficient use of time!). There's a scene with a space station shaped like a ring. It has a center body that is attached radially to one edge of the ring. This space station is...

Hello there, I was just wondering why aircraft tires are not spun up to landing speed before touching down, wouldn't this allow them to be used for much longer before they need to get retreaded? This would also cut down on the cleaning that happens on runways to remove the rubber right?

I hope this isn't too simple for this site. I have had a challenge at work trying to eliminate air bubbles from a paste in a 20oz cartridge. The cartridge has a piston in one end to push the material out and the other end tapers to a small threaded 3/8" opening. I won't take the time explain...

1. Problem: Determine the final translational speed of a spinning disc that is dropped on an infinite horizontal plane. Think of spinning up an automobile wheel suspended over a road (wheel spinning normal to the road), then dropping the wheel on the road. When the wheel rim touches the road...

How should I go about modelling a ball and spinning beam system in matlab? It's similar to the ball and beam control system except the beam spins like a propeller so the control system has to account for the centripetal force. Any reference papers?

Homework Statement A device consists of eight balls each of mass 0.78kg attached to the ends of low-mass spokes of length 2.2m, so that the radius of rotation of the balls is 1.1m. The device is mounted in the vertical plane. The axle is held up by supports that are not shown, and the wheel is...

Homework Statement If I were to drop a spinning ball vertically, the spin would cause the ball to bounce a certain horizontal difference. Intuitively, the rougher the surface it bounces against, the further the ball should bounce. How would you quantify this relationship? Homework EquationsThe...

Does the mass of a spinning object twist space time? If so is this why all natural satellites orbit in the same direction as the spin of the said object?

Is the the force that keeps the Earth spinning the same force that moves the moon farther away from us? Spinning objects are accelerating and it takes a force to accelerate an object so the force that keeps the Earth spinning is centrifugal force right?