Spinning Definition and 558 Threads

Homework Statement Hi guys, this question is from Kleppner and Kolenkow's mechanics book, problem 7.2: A flywheel of moment of inertia I rotates with angular velocity w at the middle of an axle of length 2L. Each end of the axle is attached to a support by a spring which is stretched to...

Homework Statement Problem statement: Please see the attached picture. A rigid rod rotates with constant angular velocity w. A rigid bar with length A is attached perpendicular to the rotating rod. A second rigid bar with length B is attached to the other end of bar A by a hinge. The...

hypothetical: If I were to spin with my arms outstretched, with the tips of my fingers moving at (or near) the speed of light the center of my head would therefore not be moving at all. Would the centre of me age faster than the extremeties?

Consider the following object: The exact dimensions are unimportant, but its x, y and z dimensions must not be too similar (so I'm told). I have been told that an object such as the one above will behave strangely when thrown up into the air whilst spinning. If it is sent spinning...

Homework Statement A spinning top has a moment of inertia of 0.0004 kg*m^2 and is initially at rest. It is free to rotate about a stationary axis. A string, wrapped around a peg along the axis of the top, is pulled in such a manner as to maintain a constant tension of 5.57 N in the string...

Help me!A spinning blue plastic object made me sleepless. I've seen the mit online vedio course Physics I: Classical Mechanics Lecture 21 Torques, Oscillating Bodies,near the end 44:19.There is a spinning blue plastic object,the teacher spun it, it revolved then it stoped,then it revolved...

How would I calculate the speed of a spinning wheel (using forces in Newton and anything else required)?

I would like to be able to calculate the forces on a spinning disk to determine the rpm it will fly apart given its dimensions and the mechanical properties of the material it's made of. I understand centripital and centrifugal forces. However, I'm not understanding how I to set up the problem...

Why a spinning top won't fall to the ground? yes I know this question must have been asked before right? tried looking for it on here but I couldn't find it.

We've heard of the water pipe analogy for electric circuit. It says that the current produces magnetic field and that the "pipe" is irrelevant - only the amp-turns are relevant. So I was wondering, is it possible to increase the amp-turns of a electromagnet by rotating it in the same direction...

well this is a really good question which i just thought while playing cricket. A sphere of mass m and radii r(a tennis ball) falls freely from a height of H and angular velocity(clockwise) about its axis omega.Coefficient of restitution is e The coefficient of friction is mu. After the...

spinning disk torque? Homework Statement A uniform solid disk with radius 10 cm has mass 0.7 kg (moment of inertia I = ½MR2). A constant force 12 N is applied as shown. At the instant shown, the angular velocity of the disk is 40 radians/s in the -z direction (where +x is to the right, +y...

Spinning Disk A disk with a diameter of 0.06 m is spinning with a constant velocity about an axle perpendicular to the disk and running through its center. a) How many revolutions per second would it have to rotate in order that the acceleration of the outer edge of the disk be 15 g's...

A spinning object such as a gyroscope is known to maintain its orientation. I am wondering *what* it maintains its orientation with respect *to*. One answer is itself. Something else I have read is "with respect to the distant stars". If it is not with itself but with "distant stars", one can...

Homework Statement I have three metal blocks evenly spaced in a 0.3m circle that attach to a rod in the center of the circle. The rod requires 15HP to keep rotating at 1200RPM. What would the mass of the three blocks spinning at 1200RPMs need to be in order to produce 15HP? My physics class...

Homework Statement A disk with a diameter of 0.07 m is spinning about an axle perpendicular to the disk and running through its center. a) How many revolutions per second would it have to rotate in order that the acceleration of the outer edge of the disk be 14 g's (i.e., 14 times the...

Homework Statement A string 44 cm long will break under a tension of 24 N. Two such strings are tied to a 670 gm rock, their ends 60 cm apart. The rock is spun between them. What is the maximum speed it can spin before the string breaks? (Using pythagorean theorem, you can determine the radius...

Homework Statement a long, thin rod of mass M and length L is standing stright up on a table. its lower end rotates on a frictionless pivot. a very slight push causes the rod to fall over. as it hits the table, what are (a) the angular velocity and (b) the speed of the tip of the rod...

Several years ago there were widely reported claims that gyroscopes and the like became lighter.Although these claims have generally become discredited could there be any truth to them and could proof come from theoretical reasoning?

Good day. This is a reformulation of another post which I made with the physics guys at the Forum ;) OK. Here's the scoop: Through some helpful input from another source, I have found that the following handy equation Fc (N) = 4 m pi2 n2 r / 602 can be used to determine the restraining...

If a two dimensional object (say a circle) spins, their is a zero dimensional 'point' that stays in the same place as it spins. If a three dimensional object (sphere?) spins on its axis, there is a one dimensional 'line' (its axis) such that any part of that sphere that lies on that line...

Homework Statement Is a spinning frame of reference an inertial frame of reference? Homework Equations net torque, net force = ma, equilibrium --> net force = 0, net torque = 0 I've learned that an inertial frame of reference is a frame of reference which is not accelerating. The...

Homework Statement Suppose you are standing on the center of a merry-go-round that is at rest. You are holding a spinning bicycle wheel over your head so that its rotation axis is pointing upward. The wheel is rotating counterclockwise when observed from above. For this problem, neglect...

a bucket is filled with water and tied to a rope with a length of "L=1m", the bucket is then spun in a verticle circular motion , what is the minimum frequency the bucket can be spun at in order for the water to not spill? i realize that i need to find the centripeutal force. is it mv^2/r...

Homework Statement There are two balls with masses m_a and m_b connected by a string. m_b is moving at a velocity v upwards (perpendicular to the string) and it asks for the Tension (T) in the string. Homework Equations a=(v^2)/R delta Energy of system = 0 T = m((u^2)/r) u is...

Hi all, I'm a science fiction writer working on a scene in which a character in EVA, approaching a cylindrical, spinning space station. He fires a grapple and attaches to the side of the station. What would he experience? Is this so unrealistic that no editor would ever buy the story...

Homework Statement You swing a 6.5 kg bucket of water in a vertical circle of radius 1.2 m. (a) What speed must the bucket have if it is to complete the circle without spilling any water? m=6.5 r=1.2 Homework Equations maybe f=ma f=m(v^2/r) The Attempt at a Solution What I did...

Spinning Disk problem. Due tomorrow! Help please! A disk with a diameter of 0.1 m is spinning about an axle perpendicular to the disk and running through its center. a) How many revolutions per second would it have to rotate in order that the acceleration of the outer edge of the disk be 14...

Hi, I'm just trying to find out if there is a calculation to that relates deviation from a straight line to the forward velocity and the rotation of a circular object. Essentially i have a small project that i get to prepare and work on and was thinking of trying to find the optimal bowling...

If you are reading this thread chances are you are familiar with Bruce Depalma's work and publishing's. If you are not i will briefly fill you in on the " Spinning ball Anomaly ". ([ crackpot link deleted ]) Back in the 70's Bruce Depalma did a series of tests involving spinning...

Actually I have a couple of questions. First of all, I'm new here so hello to everyone. 1) Is it possible for an object or something to rotate at the speed of light? For example, with a special record player, can a record spin at or near the speed of light or does c only refer to a straight...

Why is a space probe spinning around its own axes, when flying through space?

Ok, so the Earth spins around its axis, and around the sun; and the sun spins around the black hole at the center of the Milky Way galaxy; and that center spins around some other monster black hole at the galactic center of a cluster of galaxies, which, in turn spins about another monster...

Hi to you all, May I just say I am not a physicist or the like so my questions may seem a bit green to you all, I wish to make something and need a little bit of info please. With regards to a vacuum sphere, if I was to spin an item within it would it spin freely or would there be forces...

ok so I've got the three components of the inertia tensor (A,A,C) and I've derived expression for, using matrices, the angular velocities w1,w2,w3 (these expressions can be found online if you don't already know them). anywho, what i need to do next is use the fact that torque = rate of change...

..and he brings in his arms to decrease his moment of inertia in order to increase his angular velocity, that means the rotational kinetic energy increases. But that means there's a change in rotational kinetic energy, right? But wouldn't there be no external forces acting on him (assuming no...

Practice question for a general physics exam - I'm a 4th year undergraduate but have mostly taken astrophysics courses this year so am a bit stuck going back to general physics... Homework Statement A skater spins with angular velocity \omega = 6 rad/s with his arms extended. How fast will...

For a stationary disk, the air pressure on the platter is atmospheric pressure. For a disk spinning at 10,000 RPM, say 140 miles per hour for a 5.25 inch disk, I assume the Bernoulli effect would reduce the pressure, but because of the Ekman flow, the pressure would be more than the pressure...

Homework Statement A uniform stick 1.0 m long with a total mass of 220 g is pivoted at its center. A 3.2 g bullet is shot through the stick midway between the pivot and one end The bullet approaches at 250 m/s and leaves at 140 m/s With what angular speed is the stick spinning after the...

I was watching a video on where this guy spins a a dial or capsule or a cap (I couldn't really tell, but it was like a long thing cylinder capsule look a like) and well he gave it a quick push and the cap came to a stop and than reverses direction. What could cause this? I know that...

Before the final rocket stage the Mars lander was set spinning with an angular velocity directed along the engine force vector. I am completely lost to why they did this. By spinning the lander do they speed it up? Using the right hand rule the angular velocity vector points in the direction...

Wel, this is just crazy. I've noticed something weird about spinning tops. Most of them start loosing speed, then, just before they stop, the direction of rotation is reversed! Why?! What is the force that makes them stop for a instant and then reverse the rotation? If you have no idea...

I am slipping off my spinning disc-- Homework Statement I am taking a non calculus based physics class and have hit a wall with this one. I have a horizontal spinning disc with an Angular Acceleration of .25 rad/s^2 from rest. The disc has a radius of .05 m. A pebble is placed .025m from the...

Homework Statement Calculate the magnetic force of attraction between the northern and southern hemispheres of a spinning charged spherical shell. (ex. 5.11) Homework Equations The Attempt at a Solution I already looked at this https://www.physicsforums.com/showthread.php?t=42020. I am stuck...

In discussions, and novels, about deep space missions, we frequently read of the plan to spin the spaceship to produce artificial gravity. This intuitively makes good sense. But would it work in a ship that is very, very, very far away from any stars or other matter? That is, if the ship is...

An electron has its spin vector pointing in the positive x-direction and a magnetic field vector is turned on in the positive z-direction. Question 1. Does the spin vector turn to the positive z-direction and start to precess around the z-axis? Or does is precess around the x-axis...

A bug that has a mass mb = 4 g walks from the center to the edge of a disk that is freely turning at 21 rpm. The disk has a mass of md = 12 g. If the radius of the disk is R = 30 cm, what is the new rate of spinning in rpm? Can I have some help please?

Q # 1. the film crew CANDID CAMERA replaces person's briefcase with an identical one that contains a mounted and spinning flywheel. explain what happens when the person tries to carry the briefcase around the corner?

Homework Statement A disk with a radial line painted on it is mounted on an axle perpendicular to it and running through its center. It is initially at rest, with the line at theta 0 = -90°. The disk then undergoes constant angular acceleration. After accelerating for 3.1 s, the reference...

Homework Statement A wooden rod of negligible mass and length 85.0 is pivoted about a horizontal axis through its center. A white rat with mass 0.500 clings to one end of the stick, and a mouse with mass 0.240 clings to the other end. The system is released from rest with the rod...