What is Spinning: Definition and 579 Discussions

This youtube clip has a ride that is a spinning sphere with objects hanging by strings from the surface. (see at about 0:55) This is the only ride in the video I think is theoretically impossible (the others seem like they could be done but would be dangerous and/or costly). I think it's...

As per Newton an object that is rotating at constant angular velocity will remain rotating unless it is acted upon by an external torque. But we know that a top will stop rotating after some time. So does that mean that the external torque is the friction of the floor on which the top rotates?

Can a spinning disk lift itself in the air? Can it, afterward, advance in a chosen direction? If yes, what is the correlation between the angular speed of rotation and the advancing speed? Does it need some "fins" to catch air, similar to the helicopter blades?Thank you very much.

Homework Statement Hi everyone, My problem is fairly simple: We have a circular current loop enclosing area A, and with a constant current I. The loop is rotating about its diameter at a constant angular frequency \omega. All we need to do is find the electric dipole, and magnetic dipole...

You are the only object in space. Nothing else: If you spin around really really fast, like 500rpm or whatever, would you be able to tell that you were in fact spinning around your self? There's no ebjects around you to relate to. But would you feel a G force, like with blood rushing to your head?

why does it spin?https://www.dropbox.com/s/4ctfyymbp1i0rhp/Photo%20Feb%2003%2C%2013%2006%2032.jpg?dl=0

Homework Statement The puck in the figure shown below has a mass of 0.120 kg. Its original distance from the center of rotation is 40.0 cm, and it moves with a speed of 80.0 cm/s. The string is pulled downward 15.0 cm through the hole in the frictionless table. Determine the work done on the...

I have found an equation which gives the EMF generated in a coil when a magnet is spun near it, the equation is given as: E = FNAω × 10-8 volts. Where F is the field of the sample perpendicular to the axis of roation, N is the number of turns, A is the effective area of the coil and ω is the...

Homework Statement The Coriolis force can produce a torque on a spinning object. To illustrate this, consider a horizontal hoop of mass m and radius r spinning with angular velocity w about its veritcal axis at colatitude theta. Show that the Coriolis force due to the Earth's rotation...

Let us suppose that a cylindrical bottle is on the surface of the water (filled with air for simplicity). A little spin is given to the bottle makes it rotating around the symmetry axis of the cylinder. After a while the bottle stops rotating. How to calculate the time duration of spinning?

I've gotten a bit confused about the creation of the neutron star/pulsar, so I was hoping someone could point me in the right direction :) As fusion stops, when reaching the iron phase, the outer layers (hydrogen, helium, carbon... etc.) gets pulled in-wards do to gravity. This creates a bounce...

Hello, I would like to know the amount of torque required when the flywheel starts? I know that once at speed the flywheel doesn't require torque. I would also like to know what size of slip ring induction motor to run as the below mentioned speed. The weight of the flywheel is= 6500 kg ( wt...

Homework Statement Imagine two masses connected to each other by a string. One mass sits atop a table, while the other mass dangles below the table, as the string is fed through a hole in the center. The configuration looks like this...

Homework Statement http://web.phys.ntnu.no/~ingves/Teaching/TFY4240/Exam/Exam_tfy4240_Dec_2013.pdf http://web.phys.ntnu.no/~ingves/Teaching/TFY4240/Exam/Solution_tfy4240_Dec_2013.pdf problem 2g Homework EquationsThe Attempt at a Solution Hi, this is taken from problem 2g in the problem set...

Why does fly wheel return in opposite motion after it comes to rest due to friction?

Consider this: We have a sphere rolling down a slant, released from some height h with null velocity. At the end of the slant its potential energy will have been fully converted to kinetic energy, part translational and part rotational. Now consider this: at the end of the slant the ball enters...

If two spinning cylinders with different MoIs and angular speeds and different radii come in contact with each other at the curved surfaces, how to find out the final angular speeds given all initial parameters? There will be a friction acting at the line of contact and perpendicular to it as...

Homework Statement The problem is Problem 2 on page 3 here: http://ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/angular-momentum-1/conservation-of-angular-momentum/MIT8_01SC_problems25_soln.pdf Homework Equations 3. The Attempt at a Solution [/B] My question...

Homework Statement A space station shaped like a giant wheel has a radius 95.0 m and a moment of inertia of 5.03✕ 108 kg · m2. A crew of 150 lives on the rim, and the station is rotating so that the crew experiences an apparent acceleration of 1g. When 100 people move to the center of the...

Hi all, First of all, I just want to make it very clear that I am not referring nor meaning toward antigravity , free energy or such nonsense subjects. Eric laithwaite had a lot of misunderstanding about the gyro behavior that can be explained with Newtons laws. I just really want to...

Hello, I am really struggling with calculating the final rotation of a spinning wheel. I am not even sure if my equation for changing the velocity of the spinning wheel given a coefficient of friction is even correct so I will post it here... change in angular velocity = angular velocity *...

I think I'm not understanding some conceptual part of rotational kinematics because all the questions seem connected. I want to figure it out as best I can so please don't solve it but any hints in the right direction would be really appreciated, thanks! The Question: A stiff piece of wire is...

everyone knows, E= MC^2 + PC^2 but does that apply to spinning objects? when i was small, i always was under an impression that you can create more gravity when you spin the object(well, not classical physics fast) i mean, the displacement is 0, so wouldn't the velocity= 0 and if really gets...

Homework Statement If you have data such as time of rotation when arms are extended and the lengths of their folded and extended arms measured from the centre of the skater. I know I1ω1=I2ω2 and can work out ω from the radius and time of rotation. Where can I go from here to estimate the mass...

Homework Statement If the Earth did not spin on its axis, would the other planets still appear to move across the sky? Justify your answer. Homework Equations N/A The Attempt at a Solution If the Earth continued to rotate around the sun but NOT on it's own axis then wouldn't...

Suppose you have a bucket filled with superfluid Helium-4 and you spin it with a large angular velocity Ω, the bucket obviously has angular momentum. Spinning fast enough, the fluid develops irrotational vortex lines which carry quanta of angular momentum, while leaving the curl of the ∇xv 0...

A wooden box on a weighing scale weighs 1 kg. Inside the box is a gyroscope which is set spinning, and the box is now tilted at 45 degrees to the vertical and maintains this position due to the gyroscope inside. What is the weight shown on the scale - is it 1 kg or less than 1 kg? Why is...

One particular experiment that I remember from a visit to a Science Center is the one involving a revolving platform and a gyroscope. The user spins the gyroscope - a heavy wheel on an axle and stands on the platform which is free to rotate about its vertical axis. As I distinctly...

Watch this video: Permanent magnets moving relative to a stationary copper tube generate Eddy currents which result in Joule heating of the copper. Simple enough. Let's change the problem to a rotor with 4 (circumferential) permanent magnets rotating inside a stationary (aluminum or...

I noticed this intriguing phenomena whilst messing about in work with a perfect glass hemisphere the other day: Place the hemisphere on a surface, with the flat surface facing upwards. (Looks like a 'D' rotated 90 degrees clockwise). When I spin the hemisphere fast enough, it will spin...

how does a slow spinning gyroscope behave? does it behave as a normal fast spinning gyroscope would? if the mass of the gyro is large so that the angular momentum equals a fast spinning gyro does its precession equal a fast moving one? can anybody explain?please.

I am designing a brake system for big reel that weighs about 2500lb, spinning down on a truck that is moving at 15mph, the shaft is 2.5inch in diameter. It is rotating at 53RPM and it comes to a stop at about 45 seconds. How do i start performing calculations and the design parameters...

How do I calculate the force exerted on the fulcrum (center) from a spinning blade and the effort required to spin it. In a practical example: A spinning lawnmower blade. If the blade of length x and mass y was exchanged with a heavier longer blade how much more effort would be required...

Theoretical question about a bar spinning with unlimited angular velocity. Lets imagine we have a bar of indestructible metal and we attach this bar onto a motor which is capable of an infinite number of rpm. We have a dial next to the motor that allows us to increase the rpm of the motor. We...

Hi! I came across a toy, formed as a rod. When spinning that rod counterclockwise, the behavior is as expected. But turn the direction to clockwise spinning, it immediately slows down and ends up spinning counterclockwise. See this YouTube clip. Anyone who has an explantation of this...

Is it just equal to the external torque acting on the spinning wheel?

A solid disk with mass M and radius R is moving at t=0 on a horizontal surface in the positive x-direction with speed w_o*R/4. The friction coefficient is b. At t=0 the disk is also spinning counter-clockwise with angular velocity w_o. Thus, when viewing the disk at time t=0 you will see it...

Homework Statement Derive Euler's equation of motion for a rigid body: $$\dot{\vec{L}} + \vec{\omega} \times \vec{L} = \vec{G},$$ where ##\vec{L}## is the angular momentum in the body frame, ##\omega## is the instantaneous velocity of the body's rotation and ##\vec{G}## is the external torque...

From this figure we could see the axis of rotation of wheel is y-axis and it's translational motion is along x-axis How would I describe it's horizontal motion in terms of rotational motion The wheel is spinning and also moving horizontally along x-axis w being the angular frequency

Homework Statement "Assume you want the car to accelerate towards the right. When a wheel is spinning, the contact point with the ground is moving towards the left. The direction of the frictional force on the portion of the wheel contacting the ground is opposite to the direction of the...

EDIT : solved, thanks :)

Probably a stupid question...or possibly one with stupidly simple answer...Could this even work? I have this mechanism that generates electricity when you turn the crank (think Faraday's little doodad with copper wire and magnets) and am trying to figure out how to make this thing hands-free...

Homework Statement A chain is wrapped around a disk of radius R. The tension of chain is T. What is the coefficient of friction, if when the disk is spinning at angular velocity ω, the chain slips down? See image attached. Homework Equations II Newton law a_{centripetal} =...

So, I'm in college studying Aerospace Engineering and I'm going to enter a contest of airplane models. Summing it up, I would like to know if anyone can give any insight on if it is possible (at a reasonable price) to make a Spinning Annular Wing Model Plane (i don't really know if the name is...

Would someone be willing to explain this? Here: https://www.physicsforums.com/showthread.php?t=487058 I read the entire thread and don't understand. I need one person to explain it step by step all in one place. In my case it's not a homework question. Please don't use the Socratic method...

I am designing a test rig for my company to test seals. What i have is a shaft spinning in a fluid column that is pressurized to 30 bar. The shaft is spun by a motor and i am currently trying to figure out what motor i should select. The fluid is a C4 SAE 30 Oil, quite viscous actually. My...

Let's imagine a spoke on a spinning wheel like that of a cart wheel. Now we know and can see that the outermost particles of the spoke have a higher speed than the inner particles. As we get closer and closer to the centre, we know that the speed gets slower and slower. Here's my question...

Can somebody tell me how can a spinning top turn? I still don't uderstand, because they use some difficult terms to explain. (=.=) with the Physics theory used and whole and full explanation that a secondary student can understand. and also explain why the spinning will stop turning soon...

Moons orbit planets. Planets orbit stars. Stars sometimes orbit other stars. Stars orbit galactic centres. How to we know galaxies aren't orbiting super super super massive black holes or something along those lines. And it continues. How do we know this chain is not infinite? Thanks bros Fin

Centrifugal Force -- continue spinning indefinately in space? I believe it is correct that if you spin up an object in space, like a space ship, it will continue spinning indefinately unless/until another force is applied to stop it from spinning. Then centrifugal force would push the objects...