What is Spinning: Definition and 579 Discussions

Firstly, this is NOT a homework question although it may sound like it. My question pertains to http://youtube.com/watch?v=H5NwRfMJgOQ". My question is this: Could an Infrared Laser (there are varying power output lasers of 2W - 20mW) SPIN a paper of say 25 grams as seen in the vid on the tip...

Physic help urgent A high-speed flywheel in a motor is spinning at 500 when a power failure suddenly occurs. The flywheel has mass 36.0 and diameter 75.0 . The power is off for 34.0 and during this time the flywheel slows due to friction in its axle bearings. During the time the power is...

OK, Newton's Universal Law of Gravitation tells me the magnitude of the force I feel here on the surface of the Earth. I know the direction is towards the center of the Earth. I know g = G x Mass-of-Earth / r^2. Neglecting all the other ramifications, if the Earth stopped spinning...

I play tabletennis and it is obvious that with top spin, the ball go down faster than the one without any spin. I have try to explain by bernoulli, but it seems the result is opposite: top spin ball will drift more!. Anyone can help?

In the early days of Global Warming, the "capo di tutti global warming capi", Stephan Schneider, made his world famous public appeal to commit noble cause corruption: http://stephenschneider.stanford.edu/Publications/PDF_Papers/DetroitNews.pdf It's likely that this appeal is one of the...

Homework Statement A pencil is set spinning in an upright position. How fast must the spin be for the pencil to remain in the upright position? Assume that the pencil is a uniform cylinder of length a and diameter b. Find the value of the spin in revolutions per second for a=20cm and b=1cm...

If I wanted to prove that whilst spinning a ball attached by a string in a circle, that: F = 4 * pi^2 * r / T^2 Where F = force from tension r = radius T = period of one rotation Ie. Proving that: F is directly proportional to r F is directly proportional to m F is direction...

Homework Statement Dynamics Problem: Spinning cone with mass!? The sides of a cone make an angle "THETA" with the vertical. A small mass "m" is placed on the inside of the cone and the cone, with its point down, is revolved at a frequency "f" about its symmetry axis. If the coefficient of...

Hi, I just wanted to see some of your thoughts on this rather common physics question. Does the water always go down the plug hole in the same direction? Let the water be perfectly still before the plug is released. Feel free to elaborate, cheers.

In a gravity-less world without friction, starting with a stationary needle, would one be able to make it spin by first flicking it, to cause it to twirl (so that its axis of rotation is perpendicular to its long axis), and then tap its ends repeatedly in some way so as to cause the twirling...

I was wondering about something. Say you had a really large disk, impossibly huge, and you span it around. Presumably you could only spin it so fast that the edge of the disk cannot be spinning faster than the speed of light. But why? What stops you from spinning it just a little bit faster?

Is a spinning pseudogravity similar to centrifuge in any way. If yes, then contents in it (like air) should also separate to layers (like H2 at top and heavier gases at bottom). Is this correct? Could you help me with your ideas?

Homework Statement A car tire is 65.0 cm in diameter. The car is traveling at a speed of 20.0 m/s . What is the tire's rotation frequency, in rpm? What is the speed of a point at the top edge of the tire? What is the speed of a point at the bottom edge of the tire? Homework...

A figure skater is spinning at a rate of 1.40 rev/s with her arms outstretched. She then draws her arms into her chest, reducing her rotational inertia to 68.0% of its original value. What is her new rate of rotation? I am having trouble starting this problem. I know that (I)(alpha)...

-- A person is hanging motionless from a vertical rop over a swimming pool. She let's go of the rope and drops straight down. After letting go, is it possible for her to curl into a ball and start spinning? Justify your answer....is there going to be angular velocity? will that allow her to...

(Sorry if this belongs in Engineering and not Physics) Alright, so basically the project goes like this: Using a dowel, create a windmill (anemometer) that will have a piece of string attached. The string will then pull a load over a set distance, and the time it takes to pull that load will...

I need to find the tension of a spinning chain with mass per unit length u and angular speed w. I need to show that em waves on the chain travel at the same speed as the chains linear speed. please help if you can,

Ignoring the intense heat and pressure of subterranean environments, the difficulties of constructing a hole under such conditions, drag and friction, etc: Only a hole through the axis of rotation will provide a straight trajectory or one the passes through the exact center of a spinning...

Hi, I have a little question The precession axis of a spinning top is represented vertical in every pages I have seen. Why is that? Isn't that axis just a virtual (resulting from spinning of the precession axis) precession axis, because the precession axis must be perpendicular to momentum...

Hello Does anyone know how to model a ball (sphere) with mass spinning with an initial angular velocity that gets dropped on the floor with a coefficient of friction? And find the final angular velocity? I tried solving the problem but somehow I got a singularity. The idea I used was...

I was thinking about the valving system in a regular IC engine. The valves have huge springs on them and require a lot of force to open. The camshaft/lifter system makes for a lot of drag and lost horsepower. Instead of making the valves move up and down, why not make them spin? Imagine a a...

In GR, can a spinning object be traveling on a geodesic?

Problem: An upright rod of mass m and length L is given an impulse J at its base, 45 degrees above the horizontal, which sends the rod flying. What value should J have for the rod to land vertically again (i.e. upright on the same end at which J was applied)? I'm trying to learn from Feynman's...

In fact, This is a question I caucalated in HW. But I still dun understand the answer. Any have the idea about this question? The problem is in this link http://web.mit.edu/8.07/www/probsets/PS6s.pdf The problem No.2

Hi all! I am having trouble understanding how to create a simulation of a spinning rigid body. For each axis x, y, and z I have an angle and an angular velocity. To rotate the object each axis is rotated independently - first the rotation about the x-axis followed by the rotation about...

I have obtained Kerr's paper, "Gravitational Field Of A Spinning Mass As An Example Of Algebraically Special Metrics", and was wondering if someone would be able to provide an explanation of the mathematics, or at least some direction in which I should investigate in order to learn the...

Hi, my question is this: A solid ball with mass M, radius R, speed U0, angular speed W0 hits a wall at the angle theta0. after the hit, the ball goes away with an angle theta1, angular speed W1 and speed U1. i'm asked to find the angular momentum for the point of hit, before and after the...

Sir, Why does a spinning top precess only when its axis is inclined to the vertical direction of the gravitational field?

Hi, so a friend and I had a question a few days ago and we don't know what will happen. So, let's say that there's an infinitely rigid ball that's very large (so it doesn't deform and so that the tangential velocity at different radii are noticeably different). Now, let's say this ball...

I spent all of yesrterday going over a set of puzzles. One of them was: Assume you have a container divided into two equal sections (one on the left and one on the right). One section is filled with water and the other with air. A log is placed a long the divider between these two sections...

Why the Earth keeps on spinning?

When just browsing around I stumbled over a claimed experiment done by Dr. Bruce DePalma where he claims he has shown that you can make a spinning ball travel higher and fall faster then a non rotating ball. He claims this has no explanation in Newtonian physics...

Do you get sweets called Skittles in America, or the rest of the world? http://www.britsuperstore.com/acatalog/Skittles_Bag_55g.jpg We get them in the UK - they're fruit-flavoured sweets in the various colours of the rainbow. The other day, whilst savouring a pack in the cafe at the maths...

Another one that I can't figure out. A solid disk of mass 5.0 kg and a radius of 15.0 cm is rotating with a constant angular velocity of 10.0 rad/sec. Another disk, with the same radius but a mass of 8.0 kg, is slowly dropped upon the first disk until they rotate together. Determine the...

I read the book and looked through some sites but I don't seem to understand. I have a lab soon and I have to answer this question. What must be responsible for the pattern of tides that you see? Why? a. The moon orbits the Earth once each day. b. the Earth spins on its own axis once each...

Hi! Simple question I've got to ask. The cause of precession is the torque due to weight, causing a change in angular momentum. It's stated in my textbook that the angular momentum's magnitude remains unchanged because the torque, and hence, dL, is perpendicular to the angular momentum's...

What would be the gravitational effects on people if this happened? I figure gravitational force - centripetal force = 9.8m/s^2... so is the gravitational force much stronger then 9.8?

Hello! I have this problem I must submit by tomorrow 11 PM and I am getting the wrong answer and cannot figure out what I'm doing wrong. Any help would be great. Here is the problem: "In a "Rotor-ride" at a carnival, people are rotated in a cylindrically walled "room." (See Fig. 5-35.) The...

When a top is spinning, it won't fall down to the land as long as its angular speed is large. I can understand this phenomena from the Torque-Angular momentum perspective. Howevr, i can understand it from F=ma 's perspective. Sine its center of mass is making a circular motion around the...

Please help me answer my son's question: It seems as though the outside edge of a spinning CD is moving faster than the middle of a CD. This can't be true, right? Why is it not true mathematically speaking? Thank you. Donna

that post got me thinking. would such change in geometry change the way a string vibrates? if so, that would cause predictable changes in the properties of a particle spun arund an axis that runs through the center of the string and perpendicular to the plane on which it exists. so, spin a bunch...

What if the center part of a bicycle wheel was spinning at almost the speed of light. What would keep the outside part of the rim from spinning faster than the speed of light?

my educated guess is that with 0 radius the object would start rotating around the axe to keep the kinetic energy this would mean a transformation of translation into rotation am i correct? :rofl:

From a universe according to General Relativity can we ascertain if the Universe can be said to be spinning? Spinning relative to what is a tough question - I would say perhaps a rate of spin relative to the age of the Universe might give a framework if it can be agreed that say 1 second...

And this phenomenon also occurs in neutrons?

Hi I have physics problem which I'm stuck with. It goes like this. An amusement park ride consists of a large vertical cylinder that spins around its axis fast enough for any person inside is held up against the wall then the floor drops away. The coefficient of static friction is...

Why is it that when I hold a spinning wheel on a rotating platform, when I turn the wheel upside down, the platform rotates? Is it because the angular momentum changed dircetions? Hence applying a force to keep sability making the platform turn? Is this the same idea is a top? How it is...

Hi all, I have a question. First, a moving ball, ball A, slides straight into a ball which is standing still, ball B. The balls then collide, and ball B rebounds along, say, the Y-axis at a certain speed. Now suppose we recreate the collision, except this time, ball B is spinning on its...

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?)