Rotating Definition and 1000 Threads

Homework Statement an electron is rotating around a proton with a velocity of 2*10^6 m/s on circular path of diameter 5*10^-11 m. what is the magnetic field (B) ? the centripetal force on the electron and the magnetic force should be equal and mv^2/r = Bqv or B= mv/qr.Homework Equations...

Homework Statement A bead of mass m is threaded around a smooth spiral wire and slides downwards without friction due to gravity. The z-axis points upwards vertically. Suppose the spiral wire is rotated about the z-axis with a fixed angular velocity \Omega. Determine the Lagrangian and the...

Here for your consideration is a try at synchronizing clocks on a rim rotating at a constant angular velocity. It is restricted to two clocks, each at the opposite end of a diameter of the rim. It is based on simultaneity as determined in SR. Taylor and Wheeler in Spacetime Physics, page...

Homework Statement Its about a system like in picture. I have it solved alredy BUT I still have a problem After getting the dynamic equation by Newtonian and Lagrangian methods I solved one of them making the hipótesis of Little oscillations. This diferential equation has three solutions...

Homework Statement The problem consists of a single rotating conductor in a magnetic field as shown, I don't understand at which given numbered points where there would be a maximum and zero induced emf ? http://imagizer.imageshack.us/v2/1600x1200q90/28/7ggv.png The Attempt at a...

If I have a spinning circular disc of uniform density, how would I find the torque generated by friction, if the disc is lying flat against a table with coefficient of friction μ? τ=Fxr, but what is F, and what is r in this case?

Homework Statement Homework Equations a=v2/r f=mv2/r The Attempt at a Solution I have been able to complete this first part of the question by equating 0.7g to v2/r, solving to find v then calculating T by looking at the circumference of the cylinder and using v=d/T. I'm...

Homework Statement What is wrong with the following argument from Bernoulli's equation? Suppose a fluid in a bucket is rotating under gravity with constant angular velocity W so that velocity is: u = (-\Omega y,\Omega x, 0). Then: \frac{P}{\rho} + \frac{u^2}{2} + gz = constant...

Hi guys. The following question is related to exercise 3.7 from Rindler's SR/GR text: http://postimg.org/image/8gdx0j3gd/ Consider first the following scenario: a Born rigid rod is parallel to the ##x'## axis of a frame ##S'## and accelerating uniformly with proper acceleration ##a## along the...

What is ds^2 on a rotating disk?

Homework Statement P45) In the arrangement shown in figure, the sleeve M of mass m is fixed between two identical springs whose combined stiffness is equal to k. The sleeve can slide without friction over a horizontal bar AB. The arrangement rotates with a constant angular velocity w about a...

Homework Statement A light rigid cylinder of radius 2a is able to rotate freely about its axis, which is horizontal. A particle of mass m is fixed to the cylinder at a distance a from the axis and is initially at rest at its lowest point. A light string is wound on the cylinder, and a steady...

Homework Statement Hello, I am a bit confused on when rotational kinetic energy exists and when linear kinetic energy exists. For example when we spin a string with a ball attached to the end it has kinetic energy of 0.5mv^2 of the ball when we were solving for velocity of the ball at certain...

Homework Statement A wet floor sign is pushed on the top and it starts falling. Just before hitting the floor the upper point of the sign sign hit a foot. The weight of the sign is 5 pounds (2.27 Kg or 22.24 N). The sign is 2 feet tall (0.61 m). Homework Equations With what force and energy...

Homework Statement "A uniformly charged solid sphere, of radius R and total charge Q, is centered at the origin and spinning at a constant angular velocity ω about the z axis. Find the current density \vec{J} at any point (r,θ,\phi) within the sphere." Problem 5.6(b), p.223, from...

Homework Statement a coil starts perpendicular to a magnetic field of 0.365 tesla , it has a length of 0.15 cm and a height of 0.25 cm , it rotates with a frequency of 1800 rotation / min . it also has 30 turns calculate the mean induced Emf during quarter a rotation Homework Equations...

Homework Statement As part of a carnival game, a 0.523-kg ball is thrown at a stack of 19.5-cm tall, 0.227-kg objects and hits with a perfectly horizontal velocity of 9.9 m/s. Suppose the ball strikes the very top of the topmost object as shown to the right. Immediately after the collision...

1. Homework Statement This is my first time posting on Physics Forums. I would appreciate your help with a question I'm doing in preparation for the CAP university prize exam in February. The following question is from the 1996 CAP exam. Rod attached by frictionless pin to vertical...

Homework Statement 10kg is attached to the end of a string, which is thread through a vertical tube. The string and the tube always make a 90 degree angle. The distance from the tube to the mass is R and the velocity at which it rotates is V. How much work is done to shorten the distance...

http://www.theverge.com/2013/11/28/5154240/north-dakota-river-ice-circle-is-50-foot-wide

Homework Statement A solid cylinder is dragged over a surface by a constant force F that has an angle θ with horizontal. It rolls without friction around its symmetrical axis. The mass is M and radius is R and moment of inertia is I=\frac{1}{2}MR^2 The cylinder rolls on the surface without...

Hi guys, So here's one thing which I want to design and this thing involves a flywheel rotating at about 1000 rpm. I need to transfer this energy to another shaft which is stationary with a mechanism. The mechanism has to be actuated for only a second, and then disengaged. During engagement...

If iam using a magnetic material as a shaft. The rotating shaft in a magnetic field can cause the flow of current? resulting current flow in shaft?? please clarify me...

Homework Statement http://puu.sh/5nKxl.png Homework Equations α = ω/t τ = I*α The Attempt at a Solution CM = [232200*99 + 99/2*12500] / (107100 + 232200 + 12500) = 67.102 m τ = 43320*67.102 + 43320*(99 - 67.102) = 4288680 N α = ω/t τ = I*α τ = I*(ω/t) ω...

Homework Statement What is the angular momentum of a 0.210-kg ball rotating on the end of a thin string in a circle of radius 1.35m at an angular speed of 10.4 rad/s? Homework Equations I am using L = Iω The Attempt at a Solution I put I = (2/5)(0.210 kg)(1.35m)^2 ω = 10.4 rad /...

Dynamics -- 2 shafts rotating & connected with a clutch During the operation of a machine, two shafts rotate in opposite directions and are then connected by a clutch system. Shaft 1 has a rotational speed of 800 rev/min, a mass of 35 kg and a radius of gyration of 375 mm. Shaft 2 has a...

Homework Statement The system consists of a 20-lb disk A, 4lb slender rod BC, and a 1-lb smooth collar C. If the disk rolls without slipping, determine the velocity of the collar at the instant theta=30 degrees. The system is released from rest when theta= 45 degrees. Homework Equations v=wr...

Homework Statement Our teacher isn't very descriptive: A ring of radius "a" and resistance "R" is placed at the center of a long solenoid with "n" turns (assume the solenoid is longer and wider than the ring) with its axis lined up with that of the solenoid. Find the amount of work done to...

I figured out that θ is 30 degrees. After simplifying I still could not eliminate the xy-term: I ended up with: 10x2 - 6xy + 10y2 + 3(sqrt(3))x2 - 3(sqrt(3))y2 -32 = 0 note: the x and y terms above are in prime form (I just don't know how to show that on a forum) As you can see I still have a...

My question stems from a conversation I had recently with another physics buddy of mine and has to do with rotating reference frames and acceleration. Say, in a non-rotating reference frame you have an object with a known position. For the sake of argument, say it has a position A of 0i + 2j +...

Homework Statement A bead of mass m slides without friction on a rod that is made to rotate at a constant angular velocity ##\omega##. Neglect gravity. a. Show that ##r=r_0e^{\omega t}## is a possible motion of the bead, where ##r_0## is the initial distance of the bead from the pivot...

How is this possible? The reason spinning a bucket of water upside down keeps the water inside the bucket is because you're applying force and accelerating the bucket. But in space, there is nothing 'accelerating' the rotation of a spacecraft , it is merely in continuous Newtonian motion...

We have a bead confined on a circular hoop. The hoop is rotating around an axis tangential to it. Suppose the bead is intially at the point, farthest away from the axis, and has got some intial velocity. I have a question - in the frame of the hoop, there is a Coriolis force perpendicular to...

OK, want to see if I am using the use of rad properly here the answer seems very small. but 35 degrees isn't much for all the rotations. Answer not in book so hope these are correct.. thanks ahead.

Homework Statement A bead of mass m slides under gravity on a smooth rod of length l which is inclined at a constant angle ##\alpha## to the downward vertical and made to rotate at angular velocity ##\omega## about a vertical axis. The displacement of the bead along the rod is r(t)...

As a means of curiosity, I am working on a problem involving the rotation of various shapes. The thing that I am interested in is the cross-sectional length of the shapes as they cross the x axis. So imagine that you have a circle with a pivot point at its bottom. You then rotate it about the...

Calculate the velocity and pressure distributions in a laminar steady incompressible flow of a Newtonian liquid caused by rotation, with a constant angular velocity w(omega), of a vertical cylinder of radius R in a large bodyof liquid subjected to gravitational acceleration

Homework Statement A wheel of radius R=50cm rolls along the ground with velocity V=2m/s. A pebble released on top of the wheel so that it is instantaneously at rest on the wheel. The co-efficient of friction between wheel and pebble is μ=1. The pebble starts to slide down when it has rotated...

If I were to rotate a basin of fluid at a given angular speed, I would have two acceleration components.. one gravity and one centrifugal. What would happen if I added gravity to both components of acceleration (from tilting the basin). The fluid should move to one side correct? But, what if...

I don't have extensive knowledge of electrical engineering so I need a little help. I want to make an electrical connection, but with one small hurdle. One wire must be stationary, and the other must be allowed to rotate. How would you guys go about solving this problem? My first thought...

Homework Statement A cylinder is rotating about its axis and is placed on an inclined surface without linear velocity, the coefficient of kinetic friction between the surface and the cylinder is μk . During Δt1 it stays at the same height till the rotation stops. From that moment it takes...

Hi All, I am designing a hollow rotating drum equipment which will be filled with specialized media for wastewater purification. I need help to design the shaft diameter for the entire assembly. The Drum will be hollow with a diameter of 1.77 meter and length of 2.5 filled with some kind of...

Hello everyone, I've run across an interesting Newtonian physics problem that I'd like some input on. The problem begins with a rotating object. Let's assume it is a slender rod rotating about one end with a given mass (m), length (L) and rotational speed (ω). This results in the rod having...

Let me apologize in advance for not reading the entire rotating disk thread. I think that the following question is closely related, but if it was answered in that thread, I didn't spot it. Let us consider the following timelike congruences, which maps congruence parameters t,r,theta and z...

Hi, Since velocity is a vector quantity I assume it follows that KE must also by a vector since KE=1/2mv squared. Is it true to say a rotating object has zero total velocity since + = - and therefore the total KE is zero? Thanks

Imagine a surface that rotates with frequency f about its center, if we set a small block (or a coin, or any flat object for that matter) on the table, I wanted to calculate the maximum radius that you can place this block from the center before it starts to move outward from the center. This is...

In a different thread the Herglotz Noether theorem was brought up and it was mentioned that this theory implies it is impossible for a cylinder rotating about its vertical axis to remain Born rigid in a gravitational field even at constant altitude. This is an extension of the claim that a Born...

Homework Statement A concrete block is a uniformly dense cuboid of dimensions 40 x 20 x 10 cm, with mass M. It is constrained to rotate about an axis passing through two opposite corners and its centre of mass, with constant angular speed ω. Calculate the direction of the angular...

Imagine we have a very tall vertical cylinder like a very elongated telegraph pole, that is rotating at 200 rpm about its long axis on near perfect bearings. Initially the cylinder is sufficiently far from a black hole, that differences in gravitational time dilation between the top and bottom...

Is the Milky Way Galaxy non-rotating or rotating? Which metric is best suited: Schwarzschild or the Kerr Metric, respectively?