Spinning Definition and 558 Threads

[SOLVED] spinning pencil Homework Statement A pencil is set spinning in an upright position. How fast must the spin be in order that the pencil will remain in the upright position? Assume that the pencil is a uniform cylinder with length a and diameter b. Find the value of the spin in...

[SOLVED] spinning top Homework Statement Please confirm the following: 1) If a the tip of a top is perfectly sharp and everything else about the top is perfect and there is no air resistance, then you can put the top to sleep forever i.e. you can make it spin around the vertical axis...

I'm having a problem finding and equation that will give me the tensile stress acting on a spinning ring, like the rim of a flywheel, that is trying to "pull itself apart". The ring has no spokes or disc, but is just a ring spinning on its axis. I need to know how fast the ring can spin...

Okay, I know there is observational evidence for spinning black holes, so therefore I must be confused about something, and I want you to tell me what. If you have a star that is spinning, therefore it has orbital angular momentum (mass revolving around a point), then as it is collapsing in...

Homework Statement A 10g steel marble is spun so that it rolls at 150rpm around the inside of a vertically oriented steel tube. The tube is 12 cm in diameter. Assume that the rolling friction is small enough for the marble to maintain 150 rpm for several seconds. During this time, will the...

Homework Statement A 4.05 kg object is attached to a vertical rod by two strings as in Figure P6.11. The object rotates in a horizontal circle at constant speed 6.50 m/s. http://www.webassign.net/pse/p6-11.gif (a) Find the tension in the upper string. (b) Find the tension in the lower...

so here is my questions since the Earth is spinning, wouldn't centrifugal force make us lighter? if we were not spinning would we be heaver? how come i do not have gravity? what is gravity

[SOLVED] spinning liquid creating a parabolic shape take a container of liquid and spin it... a parcel at any given radius (r) experiences (in the rotating frame) a force outward = mass x angular speed^2 x r and a vertical force of mg. Thus the surface curves such that the tangent to the...

I'm looking to simulate a bouncing and spinning ball in two dimensions. I have the detection working fine but I'm having a little difficulty with the physics. I have a moving ball colliding with a stationary immovable wall. I would like to know the resultant velocities of the ball in terms...

Right hand rule for Spinning things... Hi, I'm havign a hard time figuring out how the right hand rule works for Angular momentum, Angular velocity and torques. Its so confusing because At university we get problems about rotating solid bodys like a disk on a rod, and when the question...

Suppose you have a very strong, spinning disc with a diameter of say 10 km in length. At the centre the centripetal velocity is approaching the speed of light, how would we observe the outer edge of the disc to be.

This is what i don't get for things spinning in circles. So let's say you tie a mass to the end of a string, and you start swinging the string around in a circle with a constant speed. In the absence of air resistance, then the net force on the mass would be the centripetal force provided by...

A wheel has eight spokes and a radius of 37.5 cm. It is mounted on a fixed axle and is spinning at 3.75 rev/s. You want to shoot a 17.0 cm long arrow through the wheel, parallel to this axle, without hitting any of the spokes. Assume that the arrow and the spokes are very thin and evenly spaced...

I'm working on a computer simulation, but I'm not sure how to approach this problem. I want to find the change in angular velocity on an object rotating on top of a flat plane. So far this is what I have: (* == multiplication not dot product) Ff x r = I * alpha Ff x r = I * dv/dt I...

A uniform disk of radius R and mass M is spinning with angular speed ωi. It is placed on a flat horizontal surface; the coefficient of kinetic friction between the disk and surface is μk. a) Find the frictional force on the disk. b) How long will it take for the disk to come to rest. I'm...

Problem 13.30 A thin, 60.0g disk with a diameter of 7.00 cm rotates about an axis through its center with 0.240 J of kinetic energy. What is the speed of a point on the rim? Homework Equations m=.06kg r=.035m KE=.240J The Attempt at a Solution K=(1/2)*I*(w^2) I=(1/2)*M*R^2 I'm using the...

Homework Statement The angular velocity of the spinning Earth is approximately... 0.26 rad/hr 6.28 rad/hr 0.13 rad/hr or none of the above I am new at this forum as of today! I hope that somebody could show me how I should even begin this! I have no idea! Homework Equations 1 rev/s=...

In my lab, we were spinning a mass (stopper) in a uniform circular motion attached to a string. The string went through a hollow tube and at the other of the string, a weight was hanged. We were trying to find out how frequency of the revolution were affected by mass, radius and tension force...

An object has rotational inertia I. The object, initially at rest, begins to rotate with a constant angular acceleration of magnitude alpha. What is the magnitude of the angular momentum L of the object after time t? ___ So I know that I have to find angular velocity and use the equation...

How do you find the Kinetic Energy of a person spinning on a chair with 2 equal weights on each arm? A specific problem asks what the change in KE is if he moves his originally extended arms inward. I tried doing (1/2)(I)(wf)^2 - (1/2)(I)(wi)^2 where wi is initial angular velocity and wf...

Check out this page: http://www.grc.nasa.gov/WWW/K-12/TRC/Aeronautics/Ping_Pong_Curve.html Here's the picture.

I did a thought experiment - suppose we have a simple clock comprising a disc rotating with constant angular velocity. We can read off time inervals by counting the revs. Another observer, passing at constant velocity will see the disc rotating at a slower rate, since moving clocks run...

Homework Statement A computer is reading data from a rotating CD-ROM. At a point that is 0.0244 m from the center of the disk, the centripetal acceleration is 283 m/s2. What is the centripetal acceleration at a point that is 0.0856 m from the center of the disc? Homework Equations Ac =...

Ages ago in my physics classes my teacher would have a large metal motor that would spin very fast, it was attached to a metal board. When he asked people to hold it it felt really strange and would pull you in apparently random directions. When it didnt spin it was very heavy but when it was...

So I have two (somewhat) related questions. 1) Why is it wheel rims (or spokes) sometimes appear to spin backward? Everytime I see this it drives me crazy. I just cannot figure out how a wheel spinning real fast in one direction appears to be spinning real slow in the other direction. 2)...

Here is a little animation of an idea I have, It's a wheel that spins continuously and is powered by magnets. Here's the link : http://www.youtube.com/watch?v=uNBVQBVOJMw" The description of the video will explain my idea. Please tell if this would work in real life.

Physics Question Applying the standard physics definition of 'spin'...If one were to take a black permanent marker and draw circles of various size in various places on the top surface of a white frisbee and throw it, would the mass inside each of those individual circles be experiencing it's...

This isn't really an aerospace problem, just basic physics. Been thinking about hardSF spaceship designs. Could someone comment on my logic and maths? The basic plan has a nuclear powerplant and a habitable section connected by a long tether. the whole contraption spins to provide cetrifugal...

Ok...I cannot remember where I had seen it...I believe it was in a science book in high school because I remember a picture being associated with it. It went something like this: Some famous physicist/scientist had a very heavy gyroscope at the end of a long metal rod. He could not lift...

When I got a stick with opposite electric charges on both ends ( a macroscopic dipole) and start slowly spinning it, I get radio waves. What happens when I keep increasing the spinning velocity, do I get the whole spectra of em waves? Does the dipole send out light at a certain spinning...

2 questions. 1.when you're spinning wheel by its shaft, does the wheel have any kinetic energy while it's spinning?is it conserved?explain why. 2.does the wheel have any net momentum while it's spinning? is it conserved?explain why

Hello, Say you have a frictionless setting. In this setting are two skateboards. One has a waterwheel (or any wheel with fins) propped up on beams so that it is on the skateboard and can freely turn. On the other skateboard is a person standing on it. If the skateboards are one behind the...

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...

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...

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...