# What is Spinning: Definition and 579 Discussions

Spinning is the twisting technique where the fiber is drawn out, twisted, and wound onto a bobbin.

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1. ### I Is anything not spinning in the Universe?

so I've started doing a few equations involving time dilation due to gravity and have been told it changes depending on if its spinning or not (like with a black hole), how different is it, and whether there is any time something won't be spinning and it needing the altered calculations
2. ### Question involving angular acceleration of a spinning wheel

wfinal=98.0 rad/s, dt=3.00s w=(37 revs/3)=>w=(37 revs*(2*pi/1))/3=>w=77.493 a=(98-77.493)/3=>a=6.8357 My answer is exactly half of the correct answer. Where did I go wrong?
3. ### Coin Slipping on a Spinning Wheel

The coin slipped in Trial 2 at a lower speed because the tangetial acceleration was higher than it was in Trial 1. The coin slips whenever a force overcome static friction. There is a force of static friction acting tangetially to the circle upon the coin causing it to accelerate. If the...
4. ### Mechanics of Spinning Around (effects on inner ear)

Suppose I stood up and spun around in a circle for about twenty seconds and stop. Then, I ask my friend to look into my eyes (as I try to look into his). He sees my eyes go back and forth and back and forth (and I cannot stop that). I vaguely recall someone telling me there is a hair (or...
5. ### Maximum angle reached by a cube placed inside a spinning cylinder

I am trying to solve a problem where we have to find the maximum angle before a cube starts sliding when said cube is placed inside a spinning hollow cylinder (the cylinder is placed horizontally). The radius of the cylinder is 0.4 m, the coefficient of static friction between the cube and the...
6. ### I Changes to a spinning skater's angular velocity

Can we describe what is happening as the skater's angular velocity increases/decreases using F=ma rather than invoking L = constant?
7. ### Stress in a spinning flywheel

I'm wonder how one could calculate the total mega pascals total mega pascals that can be applied to a spinning flywheel before it exceeds its tensile strength example: a cast iron flywheel is spinning at 10,000rpm(Tangential velocity = 104.72) it has a radius of 100mm and a weight of 500g...
8. ### I Demo of spinning object flipping its axis (intermediate axis theorem)

This video demonstrates the Dzhanibekov effect (instability when spinning arround the intermediate axis). In order to achieve the best results, is it better for the three MoI's to be close together, or for them to have widely differing values?
9. ### B Centrifugal force spinning Basketball

Hi, Looking for Centrifugal force on water droplets on my spinning Basketball at 33 RPM, 45 RPM and 78 RPM
10. ### I Conservation of angular momentum -- spinning a bicycle wheel in space

Suppose we have a rotating body like a bicycle wheel in space away from gravity. This body stops after a while due to friction between the wheel and wheel axles. Is not the conservation of angular momentum violated?
11. ### I Gravity on the Moon vs. on the spinning Earth

"If the Earth were not spinning, you would be heavier as you would feel the full force of gravity."so how does this apply to the moon? the moon does not rotate and therefore you would experience the full force of gravity as stated above,yes,,yet the appolo missions film footage showed...
12. ### Mechanics of Materials — Torsional Stress on a Spinning Shaft

Summary:: Torsional stress on freely spinning shaft? Hey guys, I’m having some confusion with a certain section of the “Torsion” chapter in my mechanics of materials book: “power transmission”. Please see the problem below. This is very easy to SOLVE (basically plug and chug with the...
13. ### Circular Motion Problem -- Ball on a String Spinning in a Vertical Circle

#F= m\frac{v^2}{r} = mw^{2}r# #m=5# #r=0.9# #F= 5\frac{v^2}{0.9} = (0.9)5w^{2}# #5\frac{v^2}{0.9} = (0.9)5w^{2}# #\frac{v^2}{0.9} = (0.9)w^{2}# #v=0.9w# then I get stuck cause I have both unknowns in one equations (i bet it has something to do with the question’s use of “minimum” but I...
14. ### I Help with translation of terminology concerning the spinning top

Has anybody a translation for the various cones describing the motion of the free symmetric top? The German expressions are "Nutationskegel" (space-fixed cone via the precession of the body-fixed symmetry axis ##\vec{e}_3'##) , and "Rastpolkegel" (space-fixed cone via the precession of the...
15. ### I Will the spinning gyroscope make the plumb fall slower?

When winding a bike wheel up in an elastic double string in the ceiling, and then let the wheel spin vertically, it unwinds more slowly than if it was not spinning. I tried it. But it if a spinning disk is placed in a solid construction like this (photo attached) , and can only rotate...
16. ### Walking around the ring on a spinning space station

When moving around a circular spinning space station (doughnut shaped) Is there any difference in the direction one goes? Is the energy expenditure the same or different? Would one ever feel like one is climbing? My gut feeling says no, as the person walking has the angular momentum matching...
17. ### I Quantum Spin - If It’s Not Spinning, What Is It Doing?

I read about quantum spin a while ago. If it’s not spinning, what is it doing?
18. ### Spinning ball deviation from straight path | Magnus effect

Let's focus on obtaining how much will the ball deviate from a straight path and assume the spin of the ball to be ##11600## rpm and ##C_L = 0.4## to be the lift coefficient A pitcher is able to make a baseball follow a curved path by impinging spin on the ball (which triggers nonsymmetric...
19. ### Power calculations for a motor spinning a turntable

Hi, I have a 1 HP motor spinning a turntable (just a wheel) weighing 1kg, diameter 25cm speed 2000rpm. (Arbitrary specs). If I have to spin a turntable with the same weight (1kg) but double the diameter (50cm) at the same speed, would I necessarily need a motor with double the power (2 HP)...
20. ### I Changing the RPM of a frictionless spinning wheel in a box

Imagine a spinning wheel built into a hand size vacuum box. There is no friction between the axe bearings of the wheel and the box. Let's say that the wheel rotates with 60 RPM. Am I right if I assume: 1. The wheel continues to rotate, approximately as if in space. 2. It is not possible to...
21. ### B Spinning Black Hole Drags Space-Time: What Causes Friction?

If a Black Hole is spinning (perhaps they all do) I have heard it distorts the 'fabric' of Space-time in the vicinity. What is the 'friction' component which allows the distortion?
22. ### Intuition on Newton's Spinning Bucket

Pls Be Kind to answer. I have understood the derivation of the parabolic shape by equating the normal force, gravity and the centrifugal force. But this derivation begins with the fact that water is at equilibrium. I want an understanding (quantitative or qualitative) of why the water which was...
23. E

### I How to introduce dissipation to a spinning top

A axisymmetric spinning top is pivoted at O. The components of the inertia tensor ##I_O## at the point ##O##, with respect to the principal axes, are denoted ##A##, ##A## and ##C##. It's Lagrangian is\mathcal{L}(\mathbf{q}, \dot{\mathbf{q}}) = \frac{1}{2} A\dot{\theta}^2 +...
24. ### Max tip speed of a spinning cable

A company called SpinLaunch claims it can get something to 2200 m/s by spinning it up on a carbon fiber composite arm. I'm trying to figure out the limit of that approach. How fast can you go with existing materials? I tried to work it out for a constant with cable with no payload (result...
25. ### B What is actually spinning in quantum spin?

Some texts say quantum spin is analogous to the spin of a planet in that it gives a particle angular momentum and a magnetic moment. However, as subatomic particles are tiny, the surfaces of charged particles would have to be moving faster than the speed of light in order to produce the measured...
26. ### Spinning Bike Wheel Example, how is angular momentum conserved?

In the classic example of a person holding a spinning bike wheel, as they flip the wheel over, angular momentum is conserved by the person/chair spinning with 2x the angular momentum of the initial wheel. Not questioning that. However, I thought ang momentum is always conserved about a...
27. ### B Is the Universe Expanding Due to Spinning?

Hello all, I recently did a thought experiment and thought, "what if the universe as a whole is spinning?" This could solve the dark energy problem, as if the universe was spinning, there would be outward pull, and therefore keep the universe expanding. And, I don't know if this means anything...
28. ### B The fastest spinning and possibly the youngest magnetar known

The magnetar was discovered already in March 2020, but the below article and accompanying video were released just few days ago, to share more recent follow up observations. https://chandra.si.edu/photo/2021/j1818
29. ### Angular Momentum: Spinning Mass

First I calculated the momentum of m1. Since m2 was at rest after the collision, all its momentum was transferred, so m1 has a momentum of 158 i hat. L=r x p, so its 916 k hat. This would also be the change in L because it was initially 0 when m1 had no velocity, so I know this is the net...
30. ### I Matter leaving a spinning galaxy

By what means can a galaxy's spin increase whereby matter is expelled from the outer reaches of the galaxy?
31. E

### Two spinning disks, did I mess up?

Hey guys, I need to check that I'm not doing something stupid. You have two uniform disc-shaped gears, one of which has twice the radius of the other [and 16 times the moment of inertia]. Initially, the larger gear is spinning at ##\omega##, and then they're suddenly meshed together. We need to...
32. ### Exploring the Physics of Spinning Astronauts with Bowling Balls

Consider this scenario: two astronauts are floating in outer space with no other frame of reference other than themselves. Relative to one another they are stationary and have no motion between them, except that one astronaut is spinning at one revolution per second. The astronaut that is...
33. ### Question about using the Lagrangian for a spinning rubber band problem

Hello, I am having trouble applying Lagrangian to this problem: 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 ##\omega## about...
34. ### Rigid body rotation problem: Mass on a cord spinning up a wheel on an axle

(I know how to solve the problem, that's not what I am looking for.) I have a problem with how I ought to understand the moment of inertia. The only torque I see applicable on the wheel is that of the tension, and so I think that ##I## should be ##m_{\text{point}}R^2##, without including all the...
35. ### Equations of motion of a block on a spinning wedge

I think that the only force acting on the wall is the normal force caused by Coriolis force, so it can be calculated this way: ##N=m2\dot r \dot \theta## But ##\dot r## is not constant, so how can I calculate it? Then, I can't calculate the acceleration either since I don't have the value of...
36. ### Spinning up a flywheel with a motor

i'm simulating a small dc motor that is driven by volt = 1.54v, current = 250 milli amps, so that gives me 0.385 watts supplied to the motor next i attached a 4mm thick circular acrylic disc as a flywheel. so in this simulation i spin up the acrylic disc as a flywheel my acrylic disc is 12cm...
37. ### Understanding Earth's Spinning Speed: A Simple Explanation

Apparently, right now the Earth is spinning at 1,000 mph! From https://www.space.com/33527-how-fast-is-earth-moving.html "Earth's spin is constant, but the speed depends on what latitude you are located at. Here's an example. The circumference (distance around the largest part of the Earth) is...
38. ### MHB Physics 12u - Two masses Spinning on a disc

A penny of mass 3.10 g rests on a small 20.0-g block supported by a spinning disk. The block is sitting at the edge of the disc at a radius of 12 cm. If the coefficient of friction between block and disk are 0.750 (static) and 0.640 (kinetic) while those for the penny and block are 0.450...
39. ### B Why does a spinning top balance better when it is spinning?

I took a spinning top out of a christmas cracker and watched it for a while. So I think a spinning top should just fall over like it does when it is at rest. Why does it "work"? It balances better when you spin it on its axis.
40. ### How fast will two spinning weighted wheels propel a 7 lb cylinder?

Hello, I am hoping someone on the forum can help me. I am designing a machine to move a cylindrical weight between to high speed rollers. The system is comprised of two weighted drive wheels being spun by motors positioned one above the other as shown in the sketch. The weighted drive wheels...
41. ### Is the Spinning Wheel's Rotation Maintained? | Investigating Kinetic Energy

Hi. I searched and found no answer to this simple question: Is the spinning wheel in this videoclip keeping the same rotation (kinetic energy) when flipped upside down and back again? (if we forget about friction)
42. ### Spinning a bucket of water in a vertical circle - Inertia

Homework Statement: How or why does inertia caused the water in a bucket not to fall out when spinning in a vertical circle. Homework Equations: Is the bucket catching the water? I know Inertia is the resistance of any physical object to any change in its velocity.
43. ### Physics - Spinning a bucket of water in a vertical circle

F = mac = (mv2 / r)
44. M

### B Filling the spool of a spinning reel with braid & monofilament

I need help on figuring how to fill a spool on a spinning reel with two different diameter fishing lines. BACKGROUND INFO: The Daiwa BG3000 spinning reel’s spool can hold 240 yds of 20 lb J-Braid line. The Daiwa J-Braid X8 Grand line comes 300 yds on a spool. J-Braid X8 Grand 20 lb line is...
45. ### Spinning objects and angular acceleration

I believe I know that when an object, in terms of linear motion, accelerates, it is being resisted by inertia, thus creating so called fictitious forces. Now, that said, how does angular acceleration affect spinning objects like say, a gymnast, when they spin around the axis of rotation? Do they...
46. ### Calculation of minimum angular velocity of a mass on a spinning plate

Problem Statement: How to calculate minumum angular velocity of a mass on a spinning plate Relevant Equations: f=mrw^2 Hi, here's the question: a) A rough horizontal plate rotates with a constant angular velocity of w about a fixed vertical axis. A particle of mass m lies on the plate at a...
47. ### B What is responsible for the spinning of a galaxy?

If you fill a sink with water and then let it drain, the water swirls due to the rotation of the Earth influencing it. During star formation, the primordial accredisk disk spins due to it's galaxy's rotation as I understand it. This being the case, what force made / makes the galaxy spin to...
48. ### B Curve Space-time from Spinning disc?

Please see attached illustration (from Discover September 2004. Einstein 100 years special issue). Is it correct that one key to Einstein's thinking is to analyze a spnning disk. That "Since the rim of the disk travels faster than the center of the disk, the theory of relativity states that the...
49. ### Lenz's Law for a rotating PM motor rotor spinning in a thin CU tube

The motor is required to operate at its resonance frequency and I am looking to add a thin-walled (0.010") copper tube inside the stator bore to add some damping. The current motor air-gap is 0.015". If I install a copper tube in the stator bore bonded to the stator and leave a 0.005" air-gap...
50. ### Spinning top's moment of inertia I (disc on shaft )

I hope you guys can help me with this problem.. A top in the form of a flat, circular disc spins on a shaft that is inclined at an angle alpha to the vertical. Now I have to find the moment of inertia I for the disc about its centre on the shaft. My attempt was building I with spherical...