Disk Definition and 819 Threads

I wasn't certain if this topic strictly belonged in the GR forum. I have read the article 'Singular disk of matter in the Cooperstock-Tieu galaxy model', by Mikolaj Korzynski (http://arxiv.org/abs/astro-ph/0508377). In it, the author finds that the singularity within Cooperstock & Tieu's...

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 q0 = -90.0°. The disk then undergoes constant angular acceleration. After accelerating for 3.15 s, the reference line...

Consider the solid S described below. The base of S is a circular disk with radius 3r. Parallel cross-sections perpendicular to the base are squares. Find the volume V of this solid. I tried this... A(x) = pi*r^2 = pi*(3r)^2 = pi*9r^2 V(x) = integral from 0 to 3r(pi*9r^2 dx) =...

[SOLVED] Angular momentum and oscillation of disk A large solid disk of mass M and radius R is mounted on a fixed axis through its center using ideal bearings. A small projectile of mass m_1 traveling with velocity v_1 collides tangentially to the slight extension and sticks to the larger disk...

[SOLVED] Angular acceleration of disk For the system below, determine the tension in each rope, the linear acceleration of each mass and the angular acceleration of the disk. \ g=10 m/s^2. Use \ I=4 kgm^2. So far I have drawn the free-body diagram for m1 and m2 \ 120 - T_1 = 12a_1 and \...

A 5.0 kg, 60-cm-diameter disk rotates on an axle passing through one edge. The axle is parallel to the floor. The cylinder is held with the center of mass at the same height as the axle, then released. What is the cylinder's initial angular acceleration? ok so this is what i think i...

A 200 g, 20-cm-diameter plastic disk is spun on an axle through its center by an electric motor. What torque must the motor supply to take the disk from 0 to 1800 rpm in 4.0s? (Given: I = ½ MR2) Relevant equations I = 1/2 MR^2 T = Ia The attempt at a...

Homework Statement An 8.0-cm radius disk with a rotational inertia of 0.12 kg m2 is free to rotate on a horizontal axis. A string is fastened to the surface of the disk and a 10-kg mass hangs from the other end. The mass is raised by using a crank to apply a 9.0-N m torque to the disk. The...

Im having trouble installing a new HD into my computer. Where can I found information, accurate and up to date, about: partitioning, formating, fdisk, MBR, , multiboot, ... thanks.

A sanding disk with rotational inertia 1.22x10^-3 kgm^2 is attached to an electric drill whose motor delivers a torque of 15.8 Nm a) find angular momentum b) find angular speed of the disk 33.0ms after the motor is turned on. L = Iω τ = Iα we can find angular acceleration with what we...

Homework Statement Two shuffleboard disks of equal mass, one orange and the other yellow, are involved in an elastic, glancing collision. The yellow disk is initially at rest and is struck by the orange disk moving with a speed of 4.40 m/s. After the collision, the orange disk moves along a...

A uniform flat disk of mass M and radius R rotates about a horizontal axis through its center with angular speed ωi. a) What is its angular momentum b) A chip of mass m breaks off the edge of the disk at an instant such that the chip rises vertically above the point at which it broke off. How...

you need to design an industrial turntable that is 48.0 cm in diameter and has a kinetic energy of 0.300 J when turning at 31.0 rpm i found that inertia of the turntable about the rotation axis is = 5.71×10^-2 kg m^2 If your workshop makes this turntable in the shape of a uniform solid...

A computer disk drive is turned on starting from rest and has constant angular acceleration. If it took 0.410 s for the drive to make its second complete revolution, how long did it take to make the first complete revolution? What is its angular acceleration, in rad/s^2 I cannot find out...

A uniform disk of radius R and mass M is spinning with angular speed ωi. It is placed on a flat horizontal surface; the coefficient of kinetic friction between the disk and surface is μk. a) Find the frictional force on the disk. b) How long will it take for the disk to come to rest. I'm...

Homework Statement NOTE: Use g=9.809 m/s^2 A solid disk of radius R and mass 2.74 kg is spinning at angular velocity 61.1 rpm about a vertical axis. A solid disk of radius 2R drops concentrically on the first (sort of like dropping an old-fashioned 33 rpm record on a 45 rpm one), so that...

Homework Statement A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is rotating at 7.0 rev/s; 83 revolutions later, its angular speed is 18 rev/s. Calculate (a) the angular acceleration (rev/s^2), (b) the time required...

Homework Statement Compute the volume of the solid formed in the first quadrant by y=x^4 and y=125x when rotated around the x axis. Homework Equations the integral for a disk is solved by taking the integral from a to b of pi R^2 The Attempt at a Solution I found the...

Problem 13.30 A thin, 60.0g disk with a diameter of 7.00 cm rotates about an axis through its center with 0.240 J of kinetic energy. What is the speed of a point on the rim? Homework Equations m=.06kg r=.035m KE=.240J The Attempt at a Solution K=(1/2)*I*(w^2) I=(1/2)*M*R^2 I'm using the...

I seem to have down 1-4 on this question but I am struggling on the rest... any help?? A circular disk of fixed radius r is used in a humidifier. It is partially submerged in water and rotates on its center. The goal is to determine the height above the water, h, at which to fix the center...

[SOLVED] Net torque of uniform disk Homework Statement A uniform disk with a mass of 34.8 kg and a radius of 0.32 m is free to rotate about a frictionless axle. Forces of 90.0 N and 125 N are applied to the disk, as the drawing indicates. What is the net torque produced by the two forces...

Homework Statement A disk of radius R has an initial mass M. Then a hole of radius (1/4)R is drilled, with its edge at the disk center (The center of mass of the cutout is in the x positive direction). Find the new rotational inertia about the central axis. Hint: Find the rotational...

Homework Statement What is the angular momentum of the 1.2kg, 3.6cm diameter rotating disk in the figure below? http://i241.photobucket.com/albums/ff4/alg5045/ex13-47.gif Homework Equations The Attempt at a Solution I tried using L = Iw. w = 600 rev/min x (1 min/60s) x 2*pi...

Homework Statement A disk and a box of equal mass are released from the top of two inclines both of which are a height h above the ground and make an angle θ to the horizontal. Let the radius of the disk be R. How much sooner does the box reach the bottom of the incline than the disk...

Homework Statement The 1.6kg, 20cm diameter disk in the figure below is spinning at 240rpm. How much friction force must the brake apply to the rim to bring the disk to a halt in 3.5s? http://i241.photobucket.com/albums/ff4/alg5045/p13-69.gif Homework Equations The Attempt at a...

The question is: Two horizontal forces F1 and F2 act on a 1.8 kg disk that slides over frictionless ice, on which an xy coordinate system is laid out. Force F1 is in the negative direction of the x-axis and has a magnitude of 3.0 N. Force F2 has a magnitude of 9.0 N. The figure below gives...

Homework Statement A ball with mass m and velocity v goes on a path tangent to a disk with radius R and a mass of M. There is a completely inelastic collision at the outer rim of the disk, and the entire system begins to spin around the axis. What was the final angular speed of the system...

A mission critical manuver requiring precise orbit information is planned for 30 days from today. Unmodeled satellite drag effects may cause substantial problems producing large X-ray flares. It must be determined if the region's potential flares will affect the atmospheric densities or not...

Hi :). I'll just start describing the problem... An ant with mass m is moving anti-clockwise on a Disk with a perpendicular rotation axis (with no friction). The disk's radius is R and it's moment of inertia - I. The velocity of the ant *in relation to the Earth* is V while the disk is...

Hi, on the net I found some equation, and would like to know if they are correct ones. http://www.upei.ca/~physics/p261/projects/flywheel1/flywheel1.htm http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html Physics: Stored energy = sum of kinetic energy of individual mass...

As we know the moment of Inertia of a disc in the center of mass equals 0.5mr^2 My Simple question is: what is the moment of inertia of the disc at any other point? as I know there is a formula that supports the distance from the center of mass, and is there a relation for 3D shapes...

I read the entry about the Ehrenfest rotating disk paradox on Wikipedia, but the entry does not actually answer my question about what happens to the circumference of the disk in the "resolution of the paradox" section. All I want to know is what happens to the circumference of the rotating...

Homework Statement A uniform solid disk of radius 7.1m and mass 30.3kg is free to rotate on a fricionless pivot through a point on its rim. [picture: http://www.wellesley.edu/Physics/phyllisflemingphysics/107_p_angular_images/figure_9.gif] If the disk is released from rest in the position...

Is there a strength and/or field density difference between ring and disk magnets? I want to know which would create stronger eddy currents when dropped through a copper tube (which one would fall slower).

Homework Statement The 20-cm-diameter disk in the figure can rotate on an axle through its center. What is the net torque about the axle? image: http://session.masteringphysics.com/problemAsset/1000963/5/knight_Figure_13_14.jpg Homework Equations τ=Frsinφ The Attempt at a...

Ive been trying to find formulas that help describe the torque needed to rotate a flat disk on a flat surface when the coefficient of friction between the 2 materials is known. The first surface is a glass window (so a vertical plane) the second surface is a rotating disk of wet sponge...

A woman with a mass of 45.0 kg is standing on the rim of a large disk that is rotating at an angular velocity of 0.490 rev/s about an axis through its center. The disk has a mass of 120 kg and a radius of 4.50 m. Calculate the magnitude of the total angular momentum of the woman-plus-disk...

A flat uniform circular disk (radius = 4.69 m, mass = 280 kg) is initially stationary. The disk is free to rotate in the horizontal plane about a frictionless axis perpendicular to the center of the disk. A 55.0-kg person, standing 1.59 m from the axis, begins to run on the disk in a circular...

A flat uniform circular disk (radius = 4.69 m, mass = 280 kg) is initially stationary. The disk is free to rotate in the horizontal plane about a frictionless axis perpendicular to the center of the disk. A 55.0-kg person, standing 1.59 m from the axis, begins to run on the disk in a circular...

Hi! What do you know about Saturn's Nord Pole hexagon? Is sure than the Saturn's hexagon is owed to nothing else but his convection. Then we ask ourselves what fact makes the convection from the Saturn's North Pole. There are two possibilities: 1). the convection is due to a temperature...

Suppose a solid disk of radius R is given an angular speed about an axis through its center and then lowered to a horizontal surface and released, the coefficient of friction between disk and surface is u. What is the distance traveled before pure rolling occurs? Conservation of Momentum...

Homework Statement A disk with width b and radius a. An element of resistance is: dR=\rho \frac{2\pi r}{bdr} How do I integrate this? Thanks in advance. :approve: Homework Equations The Attempt at a Solution

Homework Statement A flat uniform circular disk (radius = 2.50 m, mass = 1.00 102 kg) is initially stationary. The disk is free to rotate in the horizontal plane about a frictionless axis perpendicular to the center of the disk. A 55.0 kg person, standing 1.55 m from the axis, begins to run...

Homework Statement 2. a) Find the potential due to a continuous charge distribution of a disk with a surface charge, x, at point P. b) Find the electric field for part A using: attached formula . Diagram attached. Homework Equations attached. The Attempt at a Solution Well my...

A cylindrical disk has volume 8.99 × 10-3 m3 and mass 8.07 kg. The disk is floating on the surface of some water with its flat surfaces horizontal. The area of each flat surface is 0.633m2. (a) What is the specific gravity of the disk? (b) How far below the water level is its bottom surface? (c)...

I have not attempted to work on these, the only attempt I've done was look and stare at the questions and not know where to start or even begin the problem. I do not know which formula to use either. given is highlighted in bold lettering. Unfortunately i have other homework and these problems...

Homework Statement A uniform solid disk of radius (r) 6.71 m and mass (m) 38 kg is free to rotate on a frictionless pivot through a point on its rim. If facing the disk, the pivot is on the left side. The disk is then released. What is the speed of the center of mass when the disk reaches a...

Homework Statement A thin disk with a circular hole at its center, called an annulus, has inner radius R1 and outer radius R2. The disk has a uniform positive surface charge density omega on its surface. Figure's link...

Homework Statement (See the attachment) A thin string has been wound around a homogeneuos circular disk A in such a way that the disk can roll on a horizontal surface. The mass of the disk is M, and has radius R. The string goes around a small frictionless pulley C at a height 2R above te...

I was wondering about something. Say you had a really large disk, impossibly huge, and you span it around. Presumably you could only spin it so fast that the edge of the disk cannot be spinning faster than the speed of light. But why? What stops you from spinning it just a little bit faster?