Disc Definition and 397 Threads

Homework Statement How to calculate braking force generated by eddy currents. If there is a disc of radius r with conductivity K, with a magnet located at a distance r-d from the center of the disc with a magnetic field B, what is the retarding force of the magnetic field created by the eddy...

It is for my university course but I didn't find it worthy of the advanced physics section. Homework Statement A circular metallic disk of radius b rotates about an axis perpendicular to its centre with an angular velocity ω in a constant magnetic field, strength B, which lies in the same...

Homework Statement Work out the moment about the axis of a disc with off-center hole when subjected to a linear acceleration. Homework Equations Parallel-axis theorem The Attempt at a Solution Moment of inertia of offset hole: I_oh=I_h+mr^2 where I_h is MoI of hole about its center...

Is it possbile to spin a disc that has a hole in the centre like normal DVDs but without using a rotating centre shaft that is passing through the hole? The spining disc has to be supported too by a structure. Is there any mechanism to recommend?

Homework Statement I need to find the Moment of Inertia of semicircular disc to do some question. I have done these kind of questions before (Long time ago:shy:) but for some reason i can't recall how, and even when i moved to my new home, i lost my notes :cry: Please can someone put...

Homework Statement Calculate the surface charge distribution on a metal disc of radius R having total charge +q. Homework Equations The Attempt at a Solution

I think i have this right, but would like to confirm i did the right thing: Homework Statement I have a lamina disc radius R with a disc of radius r cut out of it from its centre. Total mass of the actual object is M, Find moment of inertia when lamina rotates about axis perpendicular to...

has the matter in the accretion discs for a black hole entered the BH or is it circling the actual BH?...

Homework Statement We have 3 discs, arranged as the sketch below shows. Find the moment of inertia of the whole system around the axis, passing horizontally through center of the bigger disk: 1. Two smaller disks are fixed and cannot rotate around their axes. 2. Two smaller disks can...

Homework Statement The center of mass (C) of the circular rolling disc is offset from its centroid (O) by an eccentric distance OC = \epsilon. The radius of the wheel is R. The disc is rolling without slipping at a constant rotational speed \omega by a variable torque T. Solve for this...

Hi, I have been looking at hoop stresses and the information I have found hasn't been all that useful to me as I am having a hard time converting the thermal contraction of a system into a pressure for the equation (stress=a+b/r^2). This is the thick walled hoop equation The disc is a few...

Homework Statement A thin disc if mass m, centre of mass offset from centre by h (horizontally right in diagram), and radius r rests on a rough horizonal surface. It is originally at rest and then released. No slip occurs between disc and horizontal surface. Write the equations of motions of...

Brake Disc Design- Torque Acting On Wheel Stud Bolts I have currently been working on designing a brake disc assembly. The current problem i am having is trying to workout the force acting on each wheel stud. The frictional force of the brake pad is 3.2 KN with an efective radius of...

Homework Statement I have currently been working on a group project designing a brake disc assembly. The current problem i am having is trying to workout the force acting on each wheel stud. The frictional force of the brake pad is 3.2 KN with an efective radius of 105MM from the center...

Homework Statement A solid wheel of mass M and radius R rolls without slipping at a constant velocity v until it collides inelastically with a step of height h < R. Assume that there is no slipping at the point of impact. What is the minimum velocity v in terms of h and R needed for the...

Homework Statement A large plate is balanced at its center and two students of equal mass stand at its center. The plate is rotated on a frictionless pivot about an axis through its center and perpendicular to its face. The students then begin to walk out towards opposite edges. (Select T-True...

Homework Statement A horizontal thin disc of mass M and radius R rotates about its horizontal axis through its centre with angular speed w. If a chip of mass m breaks off at the edge of the disc, what is the final angular speed of the disc? Homework Equations Initial rotational...

Homework Statement A uniform circular disc at rest has mass 10 kg and radius 0.2m. When a force of 10 N is applied tangentially to the disc for 10s, calculate the angular velocity. Given the moment of inertia, I=1/2 mr^2 Homework Equations The Attempt at a Solution Using...

Homework Statement This is not a homework question but it could be. I am trying to understand why the moment of inertia of a thin disc about its axis of rotation is 1/2 MR2. Homework Equations The rotational moment of inertia of a system of points is ^{}\summr2. The Attempt at a Solution...

Homework Statement Consider a rigid rod-plus-disc system Find the moment of inertia of the pendulum as it freely rotates about the point P. The rod has a length 0.62 m, and the disc has a radius half that. The pivot at P is a fourth of the way from the end of the rod. The rod has a mass of...

The EMF for the Faraday disc is calculated as \epsilon = \int_0^R \textbf{v} \times \textbf{B} \cdot d\textbf{l} the integration is between the disc axis (0) and its edge (R is the disc radius). As for uniformly rotating disc \boldmath v = \omega \times r and B-field is orthogonal to the...

Homework Statement consider a disc of radius 1 in the plane D in R^2 D = {(x,y) in R^2 | x^2 + y^2 <=1 } what is the marginal pdf of x and y Homework Equations The Attempt at a Solution so the joint distribution of xy is 1/Pi for x^2 + y^2 <=1 right? but how exactly? "density"...

Homework Statement Consider a disc of radius 1 in the plane D in R D = {(x,y) in R | x^2+y^2 <= 1} write the marginal pdf of x and y Homework Equations The Attempt at a Solution so the joint pdf is 1/Pi for x^2 + y^2 <= 1 <- correct? but how to I get the marginal pdfs?

1. Homework Statement Here is the link to the old thread, https://www.physicsforums.com/showthread.php?t=349730 i tried posting but it doesn't seem active. I don't understand how they get the second pdf as i tried it and got the first pdf. I also don't know how to do the double integral as...

According to this website, particles of the disc that are located at the point of contact between the ground and the disc have a velocity of zero, and the velocity of each of the particles increases as you move from the bottom of the disc to the top of the disc. How is this possible? I always...

If I have an series of discs within each other (imagine a bunch of o's within each other, the outer one the largest, the inner-most one the smallest, and I am not limited in quantity), each spinning in the same direction and each spinning from a motion source in the disc just outside it so that...

Homework Statement a disc of radius r spins uniformly around its axis at an angular velocity \omega in a clockwise motion. the center moves on the horizontal line z = r of a vertical axis Oxz of the referential Oxyz. We call R' = Cxyz, in translation compared to R= Oxyz, of origin C and we...

Hello, I would like to know how to determine the max RPM of a disc. I would think it would be the centrifugal force against the Yeild Strength. Any help would be appreciated. Thanks, Ron

I hope this is the right place to ask this. for a long time I wondered why our galaxy, or all galaxies for that matter, is more or less shaped like a disc. I assume this has something to do with the way gravity works. Yet I also assume that the simplest shape gravity would form is a sphere...

Theres a few key concepts about the disc and washer method that I can't quite grasp and I was hoping if I could get a bit of clarification. 1) How do you find your outer and inner radius? I can provide an example if needed. 2) If a problem has its function, for example f(x)= sec x...

I may have a herniated disc in my spine. I am currious by what actions the body repairs the disc? Is the ruptured material of the disc reabsorbed into the body? Can a flattened disc grow thicker with rest, does this happen while we sleep? I Have re injured my back 5 or 6 times to varying...

Homework Statement Find the maximum of |ez| on the closed unit disc. Homework Equations |ez| is the modulus of ez z belongs to complex plane Maximum Madulus Theorem - Let G be a bounded open set in complex plane and suppose f is a continuous function on G closure which is analytic in...

see diagram a circular disc of radius r has an initial angular velocity \omega and rolls down a quarter circle ramp of radius R. The initial angular velocity will be very high (e.g. 10,000 RPM) causing the disc to slip. The normalised longitudinal force (i.e. longitudinal force / maximum...

Gravitational Disc consequence!? It there some kind of reason why the solar system is in the shape of a disc, as we'll as some galaxies? Is there a gravitational consequence which result equatorial orbits?

1. f(x)= 3x2-12x / x2-6x +8 f(x) can be made continuous at x =4 by defining f(4)=6 I know that the removable disc. is at x=2 and the non removable is at x=4. So there is an asymptote at x=4. How is it possible to define it there?

How many permutations of the letters ABCDEFGH contain the string ABC? This is an example problem in my book, and the answer is 6! = 720. Could someone please explain to me the reasoning behind this (my book does a poor job explaining)? And would this reasoning apply if the string to be...

1. The problem statement, all variables and given known data A solid disk of radius 1.60 m and mass 2.30 kg rolls without slipping to the bottom of an inclined plane. If the angular velocity of the disk is 4.9 rad/s at the bottom, what is the height of the inclined plane? Homework...

In my Cal 2 class we learned the disc method to rotate an area around an axis to obtain a volume. However we only rotated a function around either the x-axis or y axis. Let's say I take the function y=x2and y=x from the interval 0 to 1 and I want to rotate the area between these functions...

Homework Statement 1. How many strings of eight English letters are there if no letter can be repeated? 2. How many strings of eight English letters are there if X is the first letter and no letter can be repeated? 3. How many strings of three decimal digits do not contain the same digit...

Homework Statement A 200 g, 42.0-cm-diameter turntable rotates on frictionless bearings at 56.0 rpm. A 20.0 g block sits at the center of the turntable. A compressed spring shoots the block radically outward along a frictionless groove in the surface of the turntable. What is the...

Homework Statement A uniform disc radius a, mass m there is rotation about an axis (z) tangental to the disc and in the plane of the disc. a point mass m is placed at the centre of the disc. what is the new moment about the axis z also show that the period of oscillations will...

The disc in question is {z: |z|<(n+1/2)pi}. I can't figure out how to apply Rouche to this. Any help would be appreciated. (This is in the context of showing all roots of zsin(z)=1 are real. I counted the zeros of zsin(z)-1 on the real axis and got 2n+2, and now I hope to get the same answer...

I've been trying to figure out the friction coefficient of some brake pads. My test fixture only allows me to pull (F2) a brake disc between two brake pads clamped around the disc with a force F1. I then measure with a load cell the maximum force required for the brake disc to slip. My...

Homework Statement Show that if a, b, c, and d are integers such that a | c and b | d, then ab | cd. Let m be a positive integer. Show that a mod m = b mod m if a ≡ b(mod m) Homework Equations | means "divides," so a | b means "a divides b" or "b can be divided by a" mod gets the...

Homework Statement S = { z | |Im(z)| < 5 }, z is a complex number Homework Equations I am trying to generate a mobius transformation w = f(z) such that it will map S onto a unit disc but I keep running into problems and contradictions. I think there is a big mistake in my attempt but I...

I have read that locomotives use eddy current braking systems, and one article mentioned that this system has also been used to charge batteries in a recovery circuit. However, I can not find details on this idea. From what I understand, the train has conducting discs attached to the wheels, and...

Homework Statement We are familiar with the problems like this: A rolling disc with a mass on it at the radius of r from the center of the disc. In this type of problems we know in advance that the mass turns with the disc and so has a circular motion. Then since this is a circular motion with...

Homework Statement A disc has radius a and rotates with angular frequency w. Magnetic flux density is B. Such a disc of mass 10^4 kg and radius 3m is rotating freely at 3000 revs/min in a field of 0.5T. A load of 10^-3 ohms is connected suddenly between the rim and the axis of the disc...

I already have Windows XP on my computer right. OK, so I was wondering if I could buy it and then install it over again. Would it delete all of my old files so that I could restart over from the ground up? I can't do System Recovery or System Restore (my pc is infected). I can barely boot the...

Homework Statement A solid uniform disk of mass 21.0 and radius 85.0 is at rest flat on a frictionless surface. The figure shows a view from above. A string is wrapped around the rim of the disk and a constant force of 35.0 is applied to the string. The string does not slip on the rim...