What is Spinning: Definition and 579 Discussions

At what rate is the flywheel spinning when the power comes back on? A high-speed flywheel in a motor is spinning at 450rpm when a power failure suddenly occurs. The flywheel has mass 44.0kg and diameter 77.0cm. The power is off for 32.0s and during this time the flywheel slows due to friction in...

Homework Statement A bead of mass m is constrained to move on a hoop of radius R which is spinning with angular velocity ω. There is no friction. Determine the angle θ at which the bead does not move for angular velocity ω. Do not consider the solution θ = 0. Homework Equations...

There is a very heated debate in a forum for airsoft that I frequent. It is about what happens to ba bb pellet when it is fired from a bb gun. Two point of contention have formed. 1. A unbalanced bb, who's geometric center is disparate from it's center of mass will wobble, or oscillate on the...

Homework Statement A uniform stick 1.2 long with a total mass of 240 is pivoted at its center. A 3.1- bullet is shot through the stick midway between the pivot and one end The bullet approaches at 250 and leaves at 140 . Homework Equations The Attempt at a Solution

Homework Statement A particular top can be approximated as a solid cylinder of mass 100 g and radius 2 cm. A string of negligible mass and length 1 m is wound around the top, which is started by pulling horizontally on the string with a constant force of magnitude 0.6 N. The top starts...

Homework Statement The chair is 10 m from the rotating vertical axis. The solid overhang stretches 6 meters from the axis. (making 4 m from end of overhang to chair on the radial axis). The chair spins at a constant speed at 1 revolution per 10 seconds. Find the angle θ the cable makes with...

Homework Statement I want to calculate the moment of inertia of a spinning disk via integration. I'm aware of the perpedicular axis theorem, but I want to integrate. Homework Equations I = ∫r^2dm The Attempt at a Solution if I set my coordinate axis op so that the origin of the...

Homework Statement Hello guys! Now this is not a homework question, but it may sound like one. If a uniform sized and massed sphere was spinning in space away from any source of forces that could affect it, wouldn't the only forces that act on it are the centripetal and centrifugal? And if this...

Homework Statement Hello guys! Now this is not a homework question, but it may sound like one. If a uniform sized and massed sphere was spinning in space away from any source of forces that could affect it, wouldn't the only forces that act on it are the centripetal and centrifugal? And if...

This may or may not be a crazy question but do centrifuges weigh more when they're spinning? Perhaps I'm misunderstanding g-force, weight and centrifugal force.

Homework Statement There's a metallic rod of length l1 which is spinning around a vertical ax which passes through its center. The ends of the rod are spinning with ω1 angular speed. Homework Equations Determine the temperature at which to heat the metal rod so that the angular speed of...

If I place a bicycle wheel on the floor, it flips over and falls down... Same is with the toy top. But when the wheel or the top spin, they remain stable. Can someone please explain the physics behind this?

Homework Statement See image. Homework Equations ωx (ωx r) = anormal αx r =atangent x=rcos*theta y=-rsin*thetaThe Attempt at a Solution I solved for w=2 k rad/s and α= -1.5 k rad/s I also got the correct answer using the cross products. My problem is I am trying to do this problem in...

Homework Statement Spinning Space Ship One way to provide artificial gravity (i.e., a feeling of weight) on long space voyages is to separate a spacecraft into two parts at the ends of a long cable, and set them rotating around each other. A craft has been separated into two parts with a...

Hello everybody. I have to admit that I feel quite troubled since long time, actually since I read the solution of a problem that I don't understand and whose wording I immediately pass to briefly relate you. I guess that many of you have heard about the Faraday's disk, that is, a spinning...

Imagine a person weighing 99kg stands on a bathroom scale. He reads 99kg. That same person then grabs a ball attached to a string that weighs 1kg together. Since he never left the scale he now reads 100kg total. Now imagine he spins the ball and string like a helicopter overhead. (Since he's a...

I'm trying to find the average velocity of a spinning propeller. v(r) = RPM C(r) / t ; C(r) = 2πr; t=(1 min) v(r) = RPM 2πr / (1 min) I'm not quite sure what to do next. I need the answer in units of velocity, but if I integrate that last equation, I won't get units of velocity. My rough...

Homework Statement A disk begins spinning from rest with angular acceleration @ = 12 rad/s^2. A small object is on the disk a distance r = 2.0 cm from the center. What is the magnitude of the net acceleration of the object after a time t = 0.25s? (alpha) @ = 12 rad/s^2 r = 2 cm t = 0.25 s...

Hi everyone. I need to create a mechanism involving a 12" diameter horizontal tire, spinning at 3000RPM, with 2kg mass. The wheel will be attached to a spinning shaft. The only thing, I need to support the wheel from the bottom using flat bearings of some sort, so it can spin freely...

Hi everyone, I am making a project involving shooting a tennis-sized ball by means of an automated mechanism. I have two horizontal wheels which are at the same height from the ground, and are spinning in opposite directions via motors. There is a space between them, a bit smaller than the...

Apparantly this one was missed, at least nothing turned up on a search. Obviously you can speculate all you want about atmosphere and winds but you can't explain away the loss of angular momentum. But then again, a long time ago, when thinking out the box was still allowed, there was a...

I had an idea of a planet that was spinning fast enough that at its equator, the outward force from the centripetal force would almost equate the planet's own gravity. However, this would change as you got closer and closer to the poles. I was just wondering what this planet might look like...

Homework Statement There is a spinning cylindrical wheel of mass 0.013 kg at a given constant angular velocity ωo (78.54 rad/s). The wheel instantaneously begins to decelerate at an unknown constant deceleration α. From when it begins to decelerate, the wheel spins a distance of θ (0.887...

I have a question about a spinning spool, there is a spool spinning and is the sistance traveled by the circumference the same as the center of the circle? You can refer to the diagram attached for a question I had trouble with from a physics olympiad. The answer was (B). Thanks in advance!

In case of a spinning top, why is it that when it is deflected, it again returns to it's original spinning track? Like suppose it is spinning. And then, we disturb it by our hand. It deflects momentarily, yet, it again returns to its own spinning axis? Can you explain the reason?

I havnt taken physics in a while and cannot remember much. But i came here to see if an idea i had was possible. The idea is that if you were to spin a magnet in space(becasue from what i remember if you spin an object in space it continues non-stop(i have bad memory though)) you can use the...

What happens when you have equal mass that is spinning about a common x and y axes as well as at the same rate(rpm)? Now I use the term mass, understanding that this is the same in a vacuum as well as within our gravitational field. I may stand corrected here. I've often wondered about...

Homework Statement There is a ball spinning on a string in a circle in a horizontal plane in a gravitational field. What is the rotational frequency w in terms of the angle of the string to the normal line of the plane of motion, the length of the string, m, and g? The original homework was...

Hello, From what I've read, I understand that a spinning disc has a torque which resists the tilting of the disc's axis. From what I understand, the higher the angular velocity of the disc is, the more the disc will resist tilting. Can anyone tell me how to calculate this torque? If there is...

Hi, I had been thinking and could not able find any answer myself. Actually, if two materials like copper or bronze(especially considerting electrode materials in seam weld design). If the electrodes are spnning on to a work sheet for weld, obviously heat would produce in the action. is...

Homework Statement A spring has mass Ms=120g and, if unstreched, length l=65cm. A boy attaches a point mass m=500g to one end of the spring. He holds the spring at the other end and spins it horizontally around his head, such that the point mass moves with speed v=12ms-1 and the spring is...

If the Earth started spinning clock wise but still in the same orbit it is in now. What would some effects be? Also if the Earth started orbiting in the opposite direction would there be any side effects? And does the Earth even spin counter clockwise? I suppose looking down from the north pole...

if a disc was spinning faster then the speed of light... would you be able to see it? and would it make a sonic boom when it past the speed of sound?

Does a spinning uniform object which is losing mass experience a change in angular velocity? It seems to me the angular momentum changes due to a change in the moment of inertia of the object, which depends on mass. The angular momentum of the object would decrease, if we just look at the...

And if so, what is the limit? Some pulsars spin very fast. more than 700 times per second, or even faster? So the centrifugal force would be very strong at the equator, threatening to rip them apart. Is there a limit on how fast a pulsar can spin before the centrifugal force would...

Homework Statement A spinning disk is rotating at a rate of 30 rad/s in the counterclockwise direction. The disk is slowing down at a rate of 6 rad/s2. Find the angle through which the disk has turned after 3 s in radians, degrees, and revolutions. Homework Equations θ=θi + ωi*t + αt^2...

Hi all, I have a conceptual question about the net force of a rotating or spinning ball attached to a string. If we have a situation such as a tether-ball game where the ball is being swung around a string at an angle to the vertical, is the net force the tension in the string, or the...

Homework Statement The resistance of the armature windings of a DC motor is 5Ω. The motor is connected to a 120V line. When the motor is spinning at full speed, it draws a current of 4A. The back EMF at full speed is: Homework Equations Pav=\frac{1}{2}I2peakR Pav=\frac{1}{2}εpeakIpeak...

Magnetic Force on Various Sides of Spinning Loop?? Homework Statement A horizontal uniform magnetic field of magnitude 0.4 T is oriented at an angle of = 65° relative to a line perpendicular to plane of a vertical, rectangular loop, as indicated in the figure. The loop has a height of 8 cm...

Homework Statement A ball (mass M: 0.250kg) is attached to a rope (length l: 1.69m) that is fixed to a point somewhere. The ball is spinning in a circle around the support point so that the rope makes an angle 37 degrees from the vertical. I have to find the magnitude of the angular momentum of...

Just in case this is confusing: I am talking about the toy (spinning top). I know that this has something to do with kinetic energy but I just don't know how to explain it.

When a bucket of water is at rest the water on the sides will rise for the following reason taken from my textbook: Water tends to cling to the walls of the glass because the adhesive forces between the molecules of water and the glass molecules are greater than the cohesive forces between...

Homework Statement The outstretched hands and arms of a figure skater preparing for a spin can be considered a slender rod pivoting about an axis through its center. When the skater's hand and arms are brought in and wrapped around his body to execute the spin, the hands and arms can be...

Hello Forum, we all know about the experiment of the spinning bucket full of water. The water does not fall if the speed of the bucket is right (at least equal to the critical speed or larger than it). If there was no bucket the water would not fall on our heads either if the water moved...

If I take a big, uniform blob of gas that is not spinning, and mark its limit as the limit of a system, then even if that big blob of gas coalesces to make a galaxy, it will not start spinning by itself: its own gravity is an internal force, and conservation of angular momentum says I need an...

Homework Statement A 60.0 kg person is stuck against the inner wall of a rotating cylinder. The radius of the cylinder is 10.0 m and the period is 2.00s. What is the minimum coefficient of static friction required to stop him from sliding? Homework Equations Fnet = (4m∏^2R)/T^2...

A bead of mass m can slide on a frictionless circular hoop in the vertical plane with radius R. When the hoop spins around the vertical axis with a rate of ω, the bead moves up the hoop by an angle θ which depends on the angular velocity of the hoop. (Pic attached) a) Find θ in terms of ω, R...

Diagram: Text from the diagram: ____________ So, where does that force (?) come from? There is no known force allowing the gravity directed to the ground to pull an unspun top toward the principal axis, as such is a horizontal force (orthogonal to this axis), unlike the vertical...

Hello Forum, I have been reading a book, the Fabric of the Cosmos, by Brian Greene. It talks about Newton investigating the behavior of water in spinning bucket... Zero motion (at rest) and uniform motion (constant velocity) are two types of motion that cannot be distinguished: we cannot...

Everyone has seen a spinning top in action, and maybe some of you have also seen how they're able to stabilize completely like shown in the attached picture. I do get that they're hard to stop spinning because of conservation of angular momentum, but that they should be able to stabilize just...