Rotating Definition and 1000 Threads

Homework Statement Two coordinate systems xyz (…fixed) and x0y0z0 (moving) coincide at time t = 0. The moving system is rotating about the …fixed z axis, which coincides with z0 axis. The angular velocity is given by ω = tk = tk0. The position vector as measured in the rotational frame is...

Homework Statement A homogenous, thin stick with the mass m and the length l is hanging from the ceiling and can rotate freely around the point P. A small ball with the mass of M is attached to the end of the stick. The small ball on the end of the stick gets hit by another small ball with...

Homework Statement Consider a bead of mass m sliding without friction on a wire that is bent in the shape of a parabola and is being spun with constant angular velocity w about its vertical axis. Use cylindrical polar coordinates and let the equation of the parabola be z = kp2. Write down the...

I wish to synchronize a thermal camera FLIR A300/600 with a test section on a rotating shaft such that whenever the section becomes orthogonal to the line of sight of the camera, an image is clicked by it automatically. The camera uses a TTL pulse input. Being a mechanical engineer, I have...

2013 edits to the sci.physics.faq "Rotating Rigid Disk in Relativity" I was just reading the sci.physics.faq http://math.ucr.edu/home/baez/physics/Relativity/SR/rigid_disk.html on the rotating disk. I was really dissapointed by the recent (2013) editorial comments. I felt that they totally...

Hello To demonstrate that we can deduce from special relativity the existence of an observer who finds that his three-dimensional space is not euclidean (a conclusion that is false in my opinion), in subsection "Behaviour of Clocks and Measuring Rods on a Rotating Body of Reference" of his...

Homework Statement Is it possible to determine the relative location of two points on a rotating rim by sending a signal that goes from one to the other, reflects, and then returns to the sender? Assume a rim, like a bicycle wheel rim without the tire or spokes; the interior surface of the...

Imagine a cylindrical space settlement. It spins about an axis to create pseudo gravity for residents, who will think that radially outward is "downward". The shape of this settlement is a toroid with a rectangular cross section. Air is pumped into make a habitable environment. Then...

I was reading a little about the behavior of non-inertial frames in relativity, since I'm interested in knowing how can we measure time on Earth and the sequence of events here. So as we know Earth is rotating and therefore the clocks on surface that are mutually at rest get desynchronized. Can...

Hi, I would like to clear some doubts over the field of a rotating magnet. I understand that in a typical alternator or generator , brushed or brushless , the current in the wires is induced because the opposite poles of either a permanent or electromagnet pass by the coils and the magnetic...

Homework Statement At t=0 a police officer is located at (0,R) on a circular platform whose radius is R and which rotates around the z axis with constant angular velocity ω. The officer's velocity at that point in time is (ωR ,0). At that time, a bird leaves the center of the platform along the...

This is NOT a HW question. I'd appreciate an explanation of the following: I would like to determine the forces acting on a mass set between two springs of constant k on a slope (the slope's angle is alpha). The slope revolves around the vertical axis with angular velocity w and the mass could...

Hello, I am looking for some direction to books or papers which may help me, When you solve the Helmholtz equation you end up with vector spherical harmonics as solutions. The Helmholtz equation is invarient under rotations which means that rotations of these solutions are also solutions...

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