Disc Definition and 397 Threads

I want to solve the following problem: Suppose B=B(0,R) be a ball in C^n, n>1. Let f be holomorphic in B and continuous on B closure. If f(a)=0 for some a in B, show that there is p in boundary of B such that f(p)=0. I assumed f(p) is non zero for every point p in boundary B and create...

Homework Statement I have a disc with radius R. One half has the charge density of +2σ and the other half has −σ. The task is to find the total charge of the disc. Homework Equations dQ=ρ2πr^2 I would use this equation if the charge density was uniform The Attempt at a Solution My first idea...

Hi, I've seen many videos of neodymium magnets sliding slowly down an inclined copper plate, or slowly down a copper tube - due to eddy current braking,but never the other way around. My question is; will a copper disc sliding down an inclined magnetic plate, or down a magnetic tube act in the...

before I ask anything I know this has been probably talked about a lot in the past from various different angles, yet when I am searching for answers I cannot find a satisfactory answer that would look at it from the perspective I wish so here is my try. I've talked with a mentor of mine about...

For my Engineering class I have to work with three other people to design a device that launchers a disc golf. So far we have a basic design plan but we are unsure if it is actually viable. Essentially there will be a platform that holds the disc in place and will be propelled by 2 to 4...

Hi, so recently I've been having problems with my back of which the root started some time ago, the story sort of goes like this, I was repairing my car a few years ago and as you know as you are leaning over the engine bay your back is in a rather uncomfortable situation as you need to reach...

Hello, I'm currently working on the design of an e-caliper and I need to this effect to determine the linear force at which the pads have to be pressed against the disc to slow down a car swiftly. The result of my calculations is that the pad of a single front brake has to be pushed with a...

In the picture the question marked spot is confusing me. Should the MI be calculated in this ugly way? That we do not consider the points in between and on dx! Why only x is taken as the distance? You may say take x+dx, resulting dx in the exapnsion and the dx from the mass to square and being...

hello, How do i calculate brake size using force of actuation? im designing a hydraulic disc braking system (only one rotor caliper located in the middle of drive shaft) for go kart and using simple pascal law, i have calculated the force of actuation of the hydraulic brake that is the force...

I just came across an August 2012 article that suggests possible first evidence for a disk of dark matter. https://phys.org/news/2012-08-plenty-dark-sun.html Here are some quotes. Astronomers at the University of Zürich, the ETH Zurich, the University of Leicester and NAOC Beijing have found...

Homework Statement Consider a disc (negligible thickness) of radius R with its center at the origin. Assume that the disc has a radially symmetric surface charge density given by ##σ(s) = \frac{A}{\sqrt{R^2-s^2}}## at a distance s from the origin, where A is some constant. You can take it for...

Ref: http://www.spaceref.com/news/viewpr.html?pid=51416 I would be very interested to see comments from knowledgeable people about this. My impression is that this is one more example of a need to remain at least somewhat skeptical about theoretical models that have not yet been validated by...

Homework Statement Given ##\epsilon## > 0, show that the unit disc contains finitely many dyadic squares whose total area exceeds π − ##\epsilon##, and which intersect each other only along their boundaries. Homework EquationsThe Attempt at a Solution I don't really understand what the problem...

Use integration methods to establish the formula A = π r^2 for the area of a disc ofradius r. so the equation of the circle is x^2 +y^2 =r^2 . i will try and find the area of one quadrant using integration. so it will be ∫ r,0 y dx so ∫ r,0 √(r^2 -x^2) dx so from here i am trying to integrate...

Homework Statement :A metallic disc of radius R is placed perpendicular to a magnetic field B.Both the magnetic field and the disc rotate with an angular velocity w about the axis of the disc.Find the induced EMF between the center and the circumference[/B]Homework Equations Motional Emf=Bvl...

I did a little experiment the other day. It involved connecting headphones to a copper disc and a battery. Then I placed a magnet under the disc. When current flows with the magnet present I get this strange sound similar to squeezing ice. What am I hearing? I don't believe it to be the...

I'm basically familiar with wings and lift. I've run into an issue with a sculpture I'm making. I have constructed a 48" disc of 1/16" perforated steel framed in a 1/4" thick by 1 1/4" steel rim. I want to attach bearings to opposite sides of the rim and allow it to spin in the wind, but I sense...

Homework Statement coefficient of kinetic friction between the disk and the surface is 0.42 gravity = 10.6 m/s disk mass = 1.75x10^9 the skid marks are 1280m long, This is due to the fact that uneven friction had set the saucer in very slow rotation around its principal axis. By...

Hello to all, first sorry about any mistakes because English is not my native language. I'm trying to solve this problem and I can't seem to find the equation of motion Homework Statement The disc and the point A both have mass m; θ(0) = 0 2. The attempt at a solution I tried to use the...

Take a disc that can rotate with respect to the rotation axis. For simplicity, let's assume that its mass is homogeneously distributed along the rotation axis, and gravity and frictional forces do not act on the disk. In the first case, the disc does not rotate. All elements of the disk have...

Homework Statement A non uniform disc of radius R has a mass of M. Its centre of gravity is located at a distance x from the centre. Find the moment of inertia of mass (moi) around the axis perpendicular to the surface passinf through the centre of gravity. Homework Equations Parallel axis...

Homework Statement A 45 RPM record is a disk with a wide hole in the center. The mass of such record is 45g. It is 7 inches in diameter, and the hole in the center has a 1.5 inch diameter. (Sorry for the odd units, this was the way it was given). Find the moment of inertia of the 45 RPM...

Homework Statement A homopolar generator consists of a metal disc of radius ##a## and a central axle which has radius ##a/4##. The disc has resistivity ##\rho## and thickness ##t##. It is rotated in a uniform magnetic field ##B## about an axis through the centre, which is parallel to ##B## and...

When you load a game from a disc into an Xbox 360, example being Call of Duty, what is the information on the disc classified as? Is it just a different form of application software like Google Chrome or are you just loading a bunch of game files from the disc?

Homework Statement A cart with mass M has four wheels (idealized as uniform discs), each of radius r and mass m, arranged symmetrically with respect to the cart. Find the acceleration of the cart when a horizontal force F is applied on it. There is no slipping between the wheels and the...

Homework Statement Homework Equations -given in question The Attempt at a Solution I am bit confused with the boundary conditions of this problem. I understand the radial stress is zero on the inside diameter and the radial stress on the outside diameter will be the reaction to the...

The situation is part of a mechanism I have been working on. It is used for a bicycle to automatically store and release energy with a spring. It is somewhat similar to a car clutch. Homework Statement Two friction discs are rotating with different angular velocities and different torques. The...

Homework Statement The flying disc except rotation moves up and down. Show that such movement will be suppressed by frictional force of air, which has a force momentum relative to the center of disc ##N=-K\omega##. What is the time profile of this process? Homework Equations ##L= T - V##...

Homework Statement A copper disc of radius 10 cm is situated in a uniform field of magnetic flux density 1.0 * 10-2 T with its plane perpendicular to the field. The disc is rotated about an axis through its centre parallel to the field at 3.0 * 103 rev min-1. Calculate the EMF between the rim...

Hello, I am familiar with how a plasma globe works, and there are plenty of resources describing them, but I'm not 100% sure how a plasma disc works. If anyone knows, I'd love to have some insight on this subject. Regards,

I am interested in what the average photon densities are within galactic environments due to non CMB sources. In extra galactic environments, the CMB certainly dominates, however as you enter more dense and luminous areas (e.g. , the galactic disc) broad spectrum photon densities from local...

Homework Statement Two metal disks, one with radius R1 = 2.50 cm and mass M1 = 0.80 kg and the other with radius R2 = 5.00 cm and mass M2 = 1.60 kg, are welded together and mounted on a frictionless axis through their common center, as in Problem 9.77. (a) A light string is wrapped around the...

Homework Statement Hi, would like to get a feedback on my answer to this question, did I do it right? In part 2 of the question is there another way to calculate distance with friction? the question is: a disc is moving on icy surface has an initial speed of 12m/s 42m until it stops 1. what...

blu ray disc has a shorter wavelength than a red laser (650nm), but how does having shorter wavelength effect storage space? answer in laypersons terms.

Why do we take the Center of mass to be on the right side rather than on the left? A uniform circular disc of radius 4a with a circular hole of radius 2a made in the disc. The mass of L is m and a particle of mass km is now fixed to L at the point P. The system is now suspended from the point S...

Homework Statement http://moodle.telt.unsw.edu.au/pluginfile.php/1602233/question/questiontext/1933161/1/1188262/Screen%20Shot%202014-04-03%20at%2011.21.21%20am.png[/B] A disc has radius r<<R and mass m = 7.8 g. When released, it rolls on its edge without skidding on the track in the sketch...

Imagine a disc witch has a radius of R=1000m and a mass M=1000kg, this disc sits on an cube that is considered static it has no velocity in any direction whatsoever. There is a light clock with the length L=17.45240644m (approximately the same as the arc length for 1 degree on the disc θ=1)...

Homework Statement This is problem 3.4 from Prucell and Morin if you have the book. Homework Equations None The Attempt at a Solution Electric field inside a conducting sphere is zero. Let P be a point on one of its equatorial plane. The field along the plane is zero. So I know the charge...

Homework Statement Find the velocity v of a general point on a plate rotating at 800 rpm which is r meters from the center. This is literally a copy and paste job. Homework Equations period = T = 1 / f ; f = frequency The Attempt at a Solution This is what I did please tell me if it is...

Ok, so here's the deal. I'm working on something that I SHOULD know the equations for after 5 years of school and a degree in mechanical engineering, but then again I can't remember why I walked into a room most times. So if ya'll could give me some guidance and at least a starting point I...

Hi Experts, I'm preparing piezo electric generator project, but when I'm searching for piezo disc for my project, i came across different sizes of piezo electric disc, but i didn't found any datasheet, My question is what's the output voltage/power difference between different diameter...

Dear users, I have a problem with a calculation. I have got an assignment. For this assignment I have to redesign the brake actuators for the brake discs of the main landing gear of th fokker 100. I have forgotten how to calculate a force that goes sideways. The sideway forces are created when...

Homework Statement A particle is fixed to the edge of a disc of negligible mass making an angle θ0 with the ground in a uniform gravitational field, and is free to rotate about the center of the disc. I need to find the equations of motion. Homework Equations The definition of the Lagrangian...

Homework Statement Problem and worked Example[/B] Homework Equations In worked example 1. Problem The Attempt at a Solution It's the part where I'm subtracting one stress from the other stress. I put it in parenthesis on the worked example. I don't think my method here is right, I've tried...

Can a rotating dielectric disc be polarized? No external electric or magnetic field .

Hi, I'm having an issue with finding a starting point for the following problem. I've looked through my magnetism and electrodynamic notes but was unable to find a starting point. Could someone please help direct me on the correct path? Thank you. Homework Statement A thin circular disc of...

Homework Statement A uniform rod AB of length L and mass m1 is connected by a pin joint to the center of a uniform disc of radius R and mass m2. The system is placed in a vertical plane (as shown in Figure 2) and released from rest with θ=45°. (a) Draw the free-body diagrams for the rod and the...

Which way does friction in a viscous disc operate? Imagine a ring consisting of ringlets. First consider a case of a pair of nearby ringlets - in the same plane, both circular orbits. If all particles of both ringlets are in circular orbits in the same plane, then they can never collide and...

Homework Statement I uploaded a figure demonstrating the problem w and i are constants and disc is horizontal. Disc mass is neglected. Vibrating mass only moves along the direction of springs -only horizontally at this position- [PLAIN]http://[url=http://postimg.org/image/yxuleosq1/]...

Homework Statement What is the field of a disc radius a, uniformly charged with surface charge density σ, for x>>a? Homework EquationsThe Attempt at a Solution I've worked out the equation for the field of a disc: ##E = ## ##\frac{\sigma x}{2 \epsilon}## ##\frac{\sqrt{a^2+x^2}-x}{x...