Disk Definition and 783 Threads

Homework Statement A uniform disk of mass M and radius R is pivoted about a point on its edge. The disk is released from rest when its center of mass is at the same height as the pivot. What is the reaction force exerted on the disk by the pivot the initial instant the disk is released? The...

Homework Statement I need to find the equation for the electric field intensity \vec{E}(\vec{R}) of a uniformly-charged disk lying in the xy-plane with radius \rho_{0} and surface charge density \rho_{s}' at any point. Homework Equations I know that a charged disk doesn't have the symmetry...

Homework Statement Figure (a) shows a disk that can rotate about an axis at a radial distance h from the center of the disk. Figure (b) gives the rotational inertia I of the disk about the axis as a function of that distance h, from the center out to the edge of the disk. The scale on the I...

Homework Statement A solid disk (mass = 5 kg, R=0.9 m) is rolling across a table with a translational speed of 8 m/s. What is the total KE of the disk? Homework Equations K = the sum of (1/2 x mass initial x velocity initial^2) (in my textbook, there are other derivations of this formula...

Homework Statement The mass center G of a 5kg wheel of radius R = 300 mm is located at a distance r = 100 mm from its geometric center C. The centroidal radius of gyration is k = 150 mm. As the wheel rolls without sliding, its angular velocity varies and it is observed that it is = 8 rad/s in...

I have a question regarding the similarity between the Biot-Savart law and the equation that gives the magnetic field inside a current loop, and the similar version of Coloumb's law that gives the electric field due to a charged ring. In the equation for a charged ring at...

I need some help with this problem. Any help would be greatly appreciated. It is due tonight. http://session.masteringphysics.com/problemAsset/1035644/7/knight_Figure_13_47.jpg Use the link above to solve the problem. Part 1) What is the magnitude of the angular momentum of the 3.1 kg...

Ok its a simple question really... say that I have to find the volume (using polar coordinates) of the solid under the paraboloid z=x^2+y^2 and above the disk x^2+y^2≤9. My approach would be to find the z value of where the cylinder and paraboloid intersect. Then find the volume of the...

Homework Statement A force of 2.2N acts tangentially to the rim of a solid 52kg disk, with a radius of 32cm. How long does it take to accelerate the disk, rotating about an axis though it's center and perpendicular to it's plane, from rest to 210 rev/min? Homework Equations Idisk=.5mr^2...

Mass being dropped on spinning disk problem NEED HELP! 1. A disk has a radius of 1.25m and a mass of 10kg. It lies flat on a smooth table and is spinning with an initial velocity of 10 rad/s about a pin at its center. A 5kg mass is dropped on it at a distance of 0.50m from its center. Find...

Homework Statement A 3.10 kg, 31.0-cm-diameter disk in the figure is spinning at 300 rpm, how much force must a brake apply that is perpendicular to the rim of the disk to bring the disc to a halt in 2.4 s.Homework Equations t=i*alpha wf=0+alpha*t t=fr*sin(theta)The Attempt at a Solution...

A uniform disk of mass Mdisk = 4 kg and radius R = 0.22 m has a small block of mass mblock = 2.1 kg on its rim. It rotates about an axis a distance d = 0.17 m from its center intersecting the disk along the radius on which the block is situated. a) What is the moment of inertia of the block...

Homework Statement Given the vectorfield \textbf{F}(r) = y^2\bold{i} + z^2\bold{j} + x^2\bold{k} and the surface S defined by a mapping (\rho,\phi) \in [0,1] \times [0,2\pi] \mapsto \bold{r}(\rho,\phi) = 4\bold{i} + (1+\rho cos(\phi))\bold{j} + (2+\rho sin(\phi))\bold{k}...

Homework Statement A small puck is placed on a disk spinning with angular speed OMEGA around axis perpendicular to the disk and passing through its center. The coefficient of static friction between the disk and the puck is MU. At what distance(s) from the center of the disk will the puck...

Comparing Rotational and Linear Motion -- block vs. disk vs. ring Homework Statement A disk and a ring, both of mass M and radius R, are placed atop an incline and allowed to roll down. A block, also of mass M, is placed atop the same frictionless incline and allowed to slide down. How do...

Homework Statement Show that the moment of inertia of a disk is 0.5 mr^2 . The Attempt at a Solution I = \int R^2 dm Using dm = \lambda dr such that m = \lambda r : = \int_{-r}^{r} R^2 \lambda dr = \frac { \lambda } {3} ( 2r^3 ) = \frac {2} {3} (\lambda r ) (r^2) = \frac {2}...

Greetings everyone, been having some problems with this question, A uniform circular disk has radius 36 cm and mass 350 g and its center is at the origin. Then a circular hole of radius 7.2 cm is cut out of it. The center of the hole is a distance 10.8 cm from the center of the disk. Find the...

rotating disk short question! Homework Statement If object is rotating on a disk with a constant angular speed, which of the following is zero? the object's tangential acceleration the object's centripetal acceleration both (a) and (b) are zero niether (a) or (b) are zero...

What criteria is used to judge the quality of an airy disk pattern?

Homework Statement Find the volume of the solid generated by revolving the shaded region about the given axis. Homework Equations I used the disk method to solve this V = int from a to b(pi * R(x)^2) The Attempt at a Solution V = int from 0 to 2( pi * (3Y/2)^2 dy) = 6pi

Homework Statement A disk is located at 0<r<1, z = 1. It has a uniform charge distribution of 200pC/m^2. A 30 \muC point charge is located at the origin. Determine the force acting on the point charge due to the electric dield produced by the disk. Homework Equations E =...

Hello, just found this forum didn't know it existed. hopefully someone can help with this. I am trying to figure out the mass moment of inertia for a half disk spining around the center axis. A full disk is I=1/2*M*R^2. Would the inertia for spining a half disk around the center axis just...

Hi, I'm not sure this falls under the homework category, but I posted this here because I think this is more of an insight question than a question for help on how to solve the excercise (which I have). I am reading Sadiku's Elements of Electromagnetism. There is an exercise reads something...

Hi everybody! I'm having some problem with the following system... I have a 2D problem, a disk is rotating with constant velocity, but there is a friction on the boundary due to the contact between the disk and the surrounding material. I'd like to find the analytical formula of the...

I just picked up an older computer (Dell with XP) to substitute for and eventually augment a machine that has turned boat-anchor on me (I'll get to that one at a later date). The main problem is the readings I get from "my computer" of the remaining "free space". Sometimes it reads as low as a...

I am trying to solve for the wavefunction for a particle inside a 2 dimensional disk of radius r_0. The conditions are: \int^{2\pi}_0 \int^{r_0}_0 |\psi|^2\, r \,dr\, d\theta = 1 Then I tried separations of variables (set psi = R(r)Theta(theta)) to solve the Schrodinger equattion. didnt'...

http://www.webassign.net/www14/symImages/5/5/e52c6d3f5c64e9f5bf52f9a215f4f2.gif V = (pi)(r^2) I tried to graph this but it seemed like the graph kept going. what do i do?

Homework Statement A uniform circular disk whose radius R is 40.0 cm is suspended as a physical pendulum from a point on its rim. (a) What is its period of oscillation? (b) At what radial distance r < R is there a point of suspension that gives the same period? R = .40 m g = 9.81...

Homework Statement "The 19.8 cm diameter disk rotates on an axle through its center. F1=18.1 N, F2=26.6 N, F3=26.6 N, F4=18.1 N, and d=4.64 cm. What is the net torque about the axle? " http://i4.photobucket.com/albums/y111/kathy_felldown/kn-pic1314.png I have two questions about this...

find the expression for the magnetic field at a distance z on the axis which passes through the centre of a disk, with a radius of R, and a charge density σ, the disk is rotating at an anular velocity of ω...

Homework Statement A circular disk of radius 30 cm is rotating with an angular acceleration of 1 radian/ s2. What is the tangential acceleration of a point on the rim of the disk? What is its centripetal acceleration if the angular speed is 3 rev / s? Homework Equations tangential...

Hello, I was reading about Faradays rotating disk paradox wherein when both the copper disk and magnet are rotated together an eddy current is induced along the radius of the copper disk. My question is if a maganitized steel disk (with one side being the N pole and the other side...

Hi, This is probably a simple question, but not for me. Seagate ST3750640AS 750GB can provide maximum data flow from disk 624 Mbit/s. How many sectors are in outer zone tracks if average rotation latency is 4.16ms? I've no idea how to calculete this

Homework Statement A solid disk of mass m = 2.2 kg and radius r = .20 m starts from rest at a height h = 3.2 m and rolls without slipping down an incline plane with an angle of 30 degrees above the horizontal. a What is the linear velocity of the disk at the bottom of the incline...

Homework Statement A solid disk starts from rest and is accelerated to 25 rad/s in 12 sec. The mass of the disk is 4 kg and the radius is 0.15 m. What was the angular acceleration of the disk? What torque was needed to do this? How much work was done on the disk in this time? Homework...

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...

when i saw how to get the electic potential of a charged disk at a point on its axis i found that the E.P on center of the disk =0 as the integration of the eq: dv = 2k(q/a^2)((r^2)+(x^2))^(.5)dr...(a) is the radius of the disk , (r) is the radius of the element and (x) is the distance...

Homework Statement http://img13.imageshack.us/img13/88/fluxm.th.jpg Homework Equations The Attempt at a Solution I am having difficulties to work this problem out. I know the formula is : http://img13.imageshack.us/img13/4883/formmix.th.jpg

Homework Statement A point mass m is attached to the rim of an otherwise uniform solid disk of mass M and radius R (in the diagram mass m is in contact with the ground). The disk is rolled slightly away from its equilibrium position and released. It rolls back and forth without slipping...

Homework Statement Ok, let's say that I have two plate disk, with an area of A and they are separated with a distance d apart from each other. I need to measure the half-life of exponential decay to calculate capacitance. I need to graph C vs x = 1/d, however how can I get C ?? Homework...

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...

[b]1. A solid uniform disk of mass 21.0 kg and radius 85.0 cm is at rest flat on a frictionless surface. A string is wrapped around the rim of the disk and a constant force of 35.0 N is applied to the string. The string does not slip on the rim. (A) When the disk has moved a distance of 3.2 m...

How do we show that the fundamental group of the disk D^2={(x,y) in RxR: x^2 +y^2< or eq. to 1} is trivial? I know how to show that the fundamental group of the circle is isomorphic to the group of the integers under addition, but for some reason, I don't see a way to show that the...

in this electrostatics question i have a disk with a radius of R, and i have a charge q placed at a distance of R/2 perpendicular to the disk from its centre. i am asked to find the flux through the disk WHAT I DID:-- here are my calculations and i diagram...

I was sitting in Physics class today while we were talking about the speed of light. I know almost every physicist will say that nothing can go faster than the speed of light. While all of these men and women know more than me, one thing they fail to realize is that every single time anyone says...

Homework Statement A computer disk is made by focusing light to a spot whose diameter is comparable to the optical wavelength. Find the number of bits that can be stored on a 10cm diameter optical disk using an infrared laser. Homework Equations Lamda λ = diametre of laser The...

A uniform disk of mass m and radius R rolls without slipping down a ramp inclined at angle q to the horizontal. Using the angle f through which it turns as a generalised coordinate, write the lagrangian, and then the Hamiltonian. Write out and solve Hamilton’s equations of motion. Ok, so...

Disk rotating problem. urgent, help pls.. Homework Statement A disk of radius 30.0cm is free to turn about an axle perpendicular to it through its center. It has very thin but strong string wrapped around its rim, and the string is attached to a ball that is pulled tangentially away from...

what is the electric flux through a disk with a radius R when a charge of q is placed at a distance of 0.5R perpendicular to the centre of the disk ?