Spinning Definition and 558 Threads

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? :smile:

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?)

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 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...