Disk Definition and 819 Threads

(@mfb posted an article about this here, I think it deserves an own thread, and I did not find one, so I start one :smile:) The comet-like composition of a protoplanetary disk as revealed by complex cyanides Karin I. Öberg, Viviana V. Guzmán, Kenji Furuya, Chunhua Qi, Yuri Aikawa, Sean M...

Homework Statement A slotted link AC is is driven by the peg P connected to a rotating disk. Point A is fixed. Determine the link's angular velocity, \omega_{ac} and acceleration, \alpha_{ac} when the angular velocity and acceleration are \omega and \alpha , respectively. \omega = 6...

Hello, I need to calculate the force applied within a clutch pack by an expanding disk. Can you guys tell me if there is anyway to do this? I am working to find the torque capacity of a centrifugal clutch using the equation: Torque Capacity = 2/3 * COF * n * F * Radius Gyration where COF =...

Homework Statement A string is wrapped around a disk of mass 2.1kg and radius 0.045m. Starting from rest, you pull the string with a constant force of 13N along a nearly frictionless surface. At the instant when the center of the disk has moved a distance 0.13m, your hand has moved a distance...

Hello Guys, I have a disk of diameter of 150mm and thickness of 10mm which is rotating at the constant speed of 100rpm. The disk is inside water which is approximately 4-5 cm below the surface. Disk is horizontal (parallel to the water surface). Disk is attached with the shaft of the motor. At...

Homework Statement A disk rotates with constant angular velocity ##ω##, as shown (attached image). Two masses, ##m_A## and ##m_B##, slide without friction in a groove passing through the center of the disk. They are connected by a light string of length ##l##, and are initially held in...

Hello, sorry for this stupid question. I struggled to find the moment of inertia of half solid thin disk (about the center of the disk) through an integration, but I couldn't get the right value. I'm pretty sure it has to be MR^2/4, but I=\int r^2 dm \\ dm=(M/A)dS With A=\pi R^2/2 I compute...

I am looking for a way to calculate the torque, hence the viscous damping coefficient per T = c*w, acting on a rotating metal disk in an oil sump. How can I go about it? Thanks! PS. I am not a ME so please forgive my ignorance.

Hey all, I'm stuck on this problem and not sure how to proceed/if I'm in the right direction. Problem: One reference frame N sits at the origin (inertial frame) while another frame, B, describes a disk rolling on a circular ring about the other frame. Picture below (A) find the direction...

Can a spinning disk lift itself in the air? Can it, afterward, advance in a chosen direction? If yes, what is the correlation between the angular speed of rotation and the advancing speed? Does it need some "fins" to catch air, similar to the helicopter blades?Thank you very much.

Homework Statement Find a linear transformation w = f(z) such that it maps the disk Δ(2) onto the right half-plane {w | Re(w) > 0} satisfying f(0) = 1 and arg f'(0) = π/2 Homework Equations w = f(z) = \frac{az+b}{cz+d} z = f^{-1}(w) = \frac{dw-b}{-cw+a} The Attempt at a Solution [/B]...

My question is about comparing the time dilation of a clock on a spinning disk versus a clock in the vicinity of a massive object. It seems there should be a connection between the two, because of the equivalence principle, but I'm missing something because I don't quite get the answer I would...

Homework Statement So I am calculating torque and power for a disk of radius 0.5 m that is subjected to a force of 50 N at its periphery and is rotating at angular velocity of 100 rad/s. Find torque and power.[/B]Homework Equations Torque= radius x Force = 0.5m *50N = 25Nm Power= dW/dt=...

Hello, first post! I'd apreciate some help on finding out the calculus for knowing the motor's torque needed for mantaining 2 vertical disks ø46cm, 30kg each at 300rpm, taking into acount 3 generic bearings friction that hypotetically is 0.5Nm friction torque I'm having some trouble trying to...

Homework Statement I changed the problem, because I understood my error I forgot a force. It's the same problem with one motor. A motor drives two disks on a support. The support is turning clockwise at w1. Disks turn at w at start. The motor M gives a force F and a counterclockwise torque...

Hi all, I am trying to calculate the torque required by the motor to rotate a disk at a constant speed. Specs are as follows: 1. Disk radius =80mm 2. Disk Thickness =2 mm 3. Disk Weight =50gm 4. Constant speed= 3000rpm(CONSTANT) 5. Motor friction torque= 1mNm 6. Disk position parallel...

Homework Statement Half disk, radius R, mass m. I need the inertia tensor about the center of mass and then find the Principal moments of inertia about another coordinate system. Struggling with the product of inertia...

Homework Statement Two particles, each of mass m, are attached one to each end of a diameter PQ of a uniform circular disk, of mass 4m, radius a with its centre at O. The system is free to rotate about a horizontal axis through A, a point on PQ such that OA = b as indicated in the diagram...

Suppose we have a large circular disk with pegs around the perimeter, and we set the disk rotating so that one pegs passes us every second. Then, we move this disk to a gravitational field, such that one side of the disk is closer to the gravitational mass than the other. From our perspective...

Homework Statement A disk of radius 0.41 m and moment of inertia 2.8 kg·m2 is mounted on a nearly frictionless axle. A string is wrapped tightly around the disk, and you pull on the string with a constant force of 52 N. What is the magnitude of the torque? torque = 21.32 N·m After a...

Homework Statement A disk of radius 10 [cm] is charged with 5E-9 [Coulon]. where on it's axis is the greatest electric field. Homework Equations The field on the axis of a charged disk: ##E=\frac{1}{4\pi\varepsilon_0}\frac{q\cdot \cos\alpha}{s^2}## The Attempt at a Solution I express...

Homework Statement Disk with radius R σ = M/A I = ∫ mr2 Homework Equations Today we learned how to derive various moments of inertia via density equations (M/L, M/A, M/V). I understand all of them except on how to get MR2/2 for a disk. The Attempt at a Solution I = ∫mr2 σ = M/A dM =...

I would like to know if kinetics energy of a disk with radius 'r', mass 'm' which turn around itself at Wb (relative rotation) and which turn around blue axis at distance 'd' is : 1/2md²Wa²+1/2mr²(Wa−Wb)² ? With Wa > Wb Look at image please.

Homework Statement A uniform disk with radius 0.390m and mass 27.0kg rotates in a horizontal plane on a frictionless vertical axle that passes through the center of the disk. The angle through which the disk has turned varies with time according to θ(t)=( 1.50rad/s)t+( 9.00rad/s2)t2 . What is...

Homework Statement The mechanism that operates the load/unload tray for holding the disk in a tabletop Blu-ray player uses nylon spur gears, a rack, and a belt drive. The gear that meshes with the rack has a module of 2.5 mm. The gears have the numbers of teeth indicated, and the two sheaves...

Hi, I'm been spending way too much time this weekend, wrestling with the equations provided in the paper [The mutual inductance of two thin coaxial disk coils in air, Babic S., DOI: 10.1109/TMAG.2004.824810], but I just can't seem to verify the results obtained in the examples in the journal...

The problem asks for an approximation for the torque needed to rotate a disk that is separated from a stationary boundary by a viscous fluid, given that \tau = \mu \frac{U}{H}. I did it first using like this: T = F R F = \tau A = \mu \frac{U}{H} \pi R^2 where U = \Omega R And thus T = \mu...

I have seen the experiments done by the US after world war II on tv and understand how impossible it would have been to fly a craft like that with Levers and Knobs. However, today we use electronics, like in the stealth bomber to allow for many actions to be taken which are the result of...

A disk of mass M and radius R is held up by a massless string. (The two ends of the string are connected to a ceiling and the disk rests on the bottom of the string.) The coefficient of friction between the disk is μ. What is the smallest possible tension in the string at its lowest point...

Homework Statement Find the potential on the rim of a uniformly charged disk (radius ##R##, charge density ##\sigma##). [Hint: First show that ##V=k(\sigma R/\pi\epsilon_0)##, for some dimensionless number ##k##, which you can express as an integral. Then evaluate ##k## analytically, if you...

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 2R from the disk. Cost analysis suggests that you...

Homework Statement We have a disk of mass M and radius R placed on a horizontal plane. A cylindrical groove of radius r is made on a diameter.Now a sphere of mass m and radius r is placed in the groove at the circumference of the disk. At t=0 the whole system is rotated with an angular...

Ok here is the question that is being asked. Note that I know how to solve it one way, but when I go about trying to solve this problem another way that I think should give the the same result, I don't end up with the same result. Question: A disk of mass M and radius R rotates at angular...

This problem came up after drawing a line on the spinning rotor of a food processor. I was idly musing about relativity (parallel motion and perpendicular motion). Maybe some ancient mathematician found the solution while working clay on their potting wheel! Here it is: A flat disk rotates...

Homework Statement A disk with momentum of inertia I1 rotates with angular velocity Wi about a vertical friction less axle. A second disk, with moment of inertia I2 and initially not rotating , drops onto the first. Because the surfaces are rough, the two eventually reach the same angular...

Homework Statement A 45 rpm record in the shape of a solid disk 25 cm in diameter and mass 0.1 kg rotates about a vertical axle through its center. A 15 g spider rides along the edge of the record. Calculate the final angular speed of the record if the spider drops off without exerting a...

1. Question: What is the moment of inertia of a thin, flat plate in the shape of a semicircle rotating about the straight side (Fig. 12.28)? The mass of the plate is M and the radius is R The diagram is attached for reference. Homework Equations Moment of Inertia: I = ∫R2dm...

Imagine points in a plane with a uniform density. To use a simple model, consider just a finite region such as the unit circle and randomly place M points into that unit circle. By uniform density, I mean that any infinitesimal area anywhere in the unit circle has the same probability of...

Homework Statement PROBLEM: You have a horizontal grindstone (a disk) that is mass m, has a radius r, and is turning at f in the positive direction. You then press a steel axe against the edge with a force of F in the radial direction. RANDOMIZED VARIABLES: m= 95 kg r= 0.33 m f= 92 rpm F= 25...

Homework Statement /* Intro, personal: I am taking Studio Physics 1 at FSU this summer semester. We have an online homework assigned weekly via a program called ExpertTA. This question has been giving me the HARDEST time and I seriously just need some help on it. I have completed and submitted...

Homework Statement A solid disk is spinning around it center with an angular velocity of 35.0 rad/s. The disk has a mass of 3.6kg and a radius of .50m. You drop a thin ring with the same radius and a mass on the disk along the same center of rotation. What is the angular velocity of the...

Homework Statement A mouse starts running on a circular path of Radius = 28m with constant speed u = 4m/s. A cat starts from the center of the path to catch the mouse. The cat always remains on the radius connecting the center of the circle and the mouse and it maintains magnitude of its...

Hi My FORTRAN is rusty and my brain is even more rusty. I want to populate an annulus with a randomly distributed set of points. Any hints or tips to get me thinking about this would be gratefully received. Thanks D

A circular disc of 10 feet radius has to carry load 5 tonnes and it has to rotate very slowly say .. 1 rpm. how much power hp motor should be used? Can Anybody help me with thie.. Man thanks in advance...

Hi everyone, For an experiment I am writing up I have to model the acceleration of a disk rolling down an incline (at an angle of θ to the ground) with various hole sizes in the center. A am aware that the moment of inertia for this object is given by 1/2m(a^2 + b^2) and that the net...

Is there a way to reinstall win7 without the disk and without losing all of my data? The only back up I have is a bit old and I can't get my external hard drive to connect. I have a rather bad virus and I can't seem to get rid of it, so I am thinking its best just to reinstall windows.

Hi Everyone, Suppose that we have cylindrical coordinates on flat spacetime (in units where c=1): ##ds^2 = -dt^2 + dr^2 + r^2 d\theta^2 + dz^2## I would like to explicitly calculate the expansion tensor for a disk of constant radius R<1 and non-constant angular velocity ##\omega(t)<1##. I...

Homework Statement A ball of clay of mass m travels with velocity v in a path tangent to a disk of radius R and mass M. The clay collides with the disk tangentially to its outer rim (a totally inelastic collision) and the clay and disk begin to spin about the axis. What is the final angular...

Homework Statement a disk of radius 40 cm is rotating about an axis through its centre. the moment the inertia of the disk is 0.015 kg m^2 and it is turning at 3 rev/s. sand falls on the disk at a distance of 20 cm from the axis and builds a 20 cm radius sand ring on the disc. How much sand...

Homework Statement A solid, Uniform disk of radius 5.00 cm and mass 1.50 kg is rolling without slipping a long a horizontal surface. The disk makes 2.00 revolution per second a. Find the total kinetic energy (translational + rotational) of the disk b. Find the minimum height h of the...