Disk Definition and 819 Threads

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...

I'm at the library, and while studying for my last final, I am running disk defragmenter on my laptop. It has been running for a little over 3 hours now and the library closes in 20 minutes. If it is not finished by the time the library closes, will I have to wait another 3+ hourswhen I get...

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 ?

Homework Statement Imagine a frictionless pulley (a solid cylinder) of unknown mass M and radius r = 0.200 m which is used to draw water from a well. A bucket of mass m = 1.50 kg is attached to a massless cord wrapped around the pulley. The bucket starts from rest at the top of the well and...

Homework Statement A uniform disk of mass M and radius a can roll along a rough horizontal rail. A particle of mass m is suspended from the center C of the disk by a light inextensible string b. The whole system moves in a vertical plane through a rail. Take as generalized coordinates x...

Homework Statement A uniform disk of mass Mdisk = 4.1 kg and radius R = 0.3 m has a small block of mass mblock = 2.9 kg on its rim. It rotates about an axis a distance d = 0.16 m from its center intersecting the disk along the radius on which the block is situated. a) What is the moment of...

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...

Disk method question Use the disk method to find the volume of the solid obtained by rotating the region bounded by y=x^2 and y=x about the line y=x.

I currently have an iso of a program inwhich I would like to install on my home desktop. However my home desktop only has a cd-rom drive and not a dvd room drive so I can't burn it to the disk. I know I can still mount and run it using a program such as daemontools however I don't know of a way...

I've attached a .pdf with the problem explanation, questions, and answers. I can't figure out for the life of me how to get these answers though. I've setup a countless number of integrals and can't seem to get it right. Any help you guys can give me would be greatly appreciated. *EDIT* Not...

How many zeros inside the unit disk does the following function have? f(z) = 3 z^621 - e^z. (in words, three times z to the power 621 minus e^z :) ...argument principle answers this question, but I have a problem evaluating the integral of f'(z)/f(z).

Can the surface of a hemisphere be distinguished from a disk without introducing a metric? What is the minimum amount of info we need to know to identify one space as a disk and the other as the surface of hemisphere? Both can have the same coordinate chart. For example, distance from...

Homework Statement y=\sqrt{x}, x=4, y=0 Homework Equations \pi\int^{c}_{d}{R(y)}^{2}dy The Attempt at a Solution I solve for x then pluged it into the formula \int^{2}_{0}{(y^{2})^{2}} The answer I got was \frac{32\pi}{5} but my textbook says the answer should be...

Homework Statement A circular plastic disk with radius R = 1.80 cm has a uniformly distributed charge of Q = + 2.15 106 e on one face. A circular ring of width 30 µm is centered on that face, with the center of the ring at radius r = 0.50 cm. What charge is contained within the width of the...

Homework Statement Suppose you design an apparatus in which a uniformly charged disk of radius R is to produce an electric field. The field magnitude is most important along the central perpendicular axis of the disk, at a point P at distance 2.60R from the disk. Cost analysis suggests that...

disk on a plank -- HELP! Homework Statement a disk of mass M is sitting on a plank of length l and mass m. a constant force F is pulling the plank to the right. assuming no slipping what are the accelerations? how far to the right will the coin move before reaching the left end of the...

A circular disk of radius r is used in an evaporator and is rotated in a vertical plane. It is to be partially submerged in the liquid so as to maximize the exposed wetted area of the disk. show that the center of the disk should be positioned at height r/sqrt(1+pi^2) ok i absolutely know how...

A uniform disk is lying on a flat, frictionless surface, and a force is applied as shown: http://www.freeimagehosting.net/uploads/ae622047b5.jpg What will be the motion of the disk.. more importantly, the motion of center of mass of the disk. will it move in a straight line, or will it move...

Hi, How do integrate this? I wish to see it step by step and I'm glad for any help i can get. \int_{ \vec{r}\in{A}} \frac{ \vec{v}+ \vec{\omega}\times\vec{r}}{| \vec{v}+ \vec{\omega}\times\vec{r}|}d^{2}r where A is area of disk with radius R.

Homework Statement A string is wrapped around a uniform disk of mass M = 2.5 kg and radius R = 0.05 m. (Recall that the moment of inertia of a uniform disk is (1/2)MR2.) Attached to the disk are four low-mass rods of radius b = 0.09 m, each with a small mass m = 0.7 kg at the end. The device...

Homework Statement A uniform disk (like a record turntable) turns with a frequency of 5.2 rev/s around a frictionless spindle. A non-rotating rod of the same mass as the disk and length equal to the disk's diameter is placed on the freely spinning disk so both turn around the spindle. (Idisk...

Homework Statement A uniform disk is set into rotation with an initial angular speed about its axis through its center. While still rotating at this speed, the disk is placed in contact with a horizontal surface and released. What is the angular speed of the disk once pure rolling takes place...

Homework Statement A 250 g , 20.0-cm-diameter plastic disk is spun on an axle through its center by an electric motor. Homework Equations What torque must the motor supply to take the disk from 0 to 2000 rpm in 4.50 s? The Attempt at a Solution I know that Torque = Inertia times angular...

Comments ---------- hey, I am trying to figure out the moment of inertia with respect to various axis. I am, having trouble figuring out how to find out dm. I know that dm = (rho)*t*dA, but i am having trouble figuring out the t*dA part. i tried using t*dA = (pi)(r^2)/2 That didn't...