Disk Definition and 819 Threads

Homework Statement A stationary uniform-density disk of radius 0.8m is mounted in the vertical plane. The axle is held up by supports that are not shown and is frictionless. The disk has a mass of 3.6 kg. A lump of clay with mass 0.3 kg falls and sticks to the outer edge at <-0.48, 0.64...

Homework Statement Suppose a disk of radius 'r' is rotation on a surface. If the center G moves a distance 'd', then what is the distance traveled by a point on the top of the disk (on its edge or circumference). Homework Equations theta = s / r ; where theta is the rotation in rad, s is...

Diameter of disk? Question: Consider a flywheel made of iron, with a density of 7800 , in the shape of a uniform disk with a thickness of 12.4 . What would the diameter of such a disk need to be if it is to store an amount of kinetic energy of 14.6 when spinning at an angular velocity of 91.0...

A solid sphere and a solid disk are released from rest at the top of the ramp. The inclination angle is theta to the horizontal and the vertical height of the ramp is h. Determine the time difference between the objects for them to read the bottom of the ramp. This is what I've solved...

A uniform disk is attached at the rim to a vertical shaft and is used as a cam. The disc has a diameter of 38 cm. The moment of inertia of the disk about the axis of the shaft is 7.5*10^-3 kg*m/s. The shaft rotates uniformly about its axis at 70 rpm. The mass of the disc is closest to: a.0.12...

A solid disk rotates at an angular velocity of 0.094 rad/s with respect to an axis perpendicular to the disk at its center. The moment of inertia of the disk is 0.12 kg·m2. From above, sand is dropped straight down onto this rotating disk, so that a thin uniform ring of sand is formed at a...

Hey guys, does anyone know how to approach these two problems ... can u please help me ? Question 1. A magnetic computer disk 8.0 am in diameter is initially at rest. A small dot is painted on the edge of the disk. The disk accelerates at 600 rad/s2 for ½ s, then coasts at a steady angular...

A horizontal platform in the shape of a uniform circular disk rotates on a frictionless bearing about a vertical axle through the center of the disk. The platform has a mass of 150 kg, and radius of 2.00 m. A 60kg student walks slowly from the rim of the platform toward the center. If the...

A sanding disk with rotational inertia 1.2E-3 kg m^2 is attached to an electric drill whose motor delivers a torque of magnitude 16 N m about the central axis of the disk. About that axis, and with the torque applied for 33 ms, (a) What is the magnitude of the angular momentum of the disk...

ok, so a thread with hanging mass at the end is wrapped around a disk. the disk is dropped and mass is released. how do you find the kinetic energy of the weight at a given time/distance fallen from the disk? I'm not sure to whether use rotational kinetic energy or linear kinetic energy... all...

How do I determine the theoretical burst speed of a rotating disk, such as a flywheel? I went through my physics textbooks from 30 years ago with no luck. I googled, and found WAY too much information, but still no equation. Is this similar to the formula for hoop stress in a pressure...

Has the existence of a planetary disk condensed as a rigid aggregate ever been postulated or observed?

Hear I go *clears throat* "I/O, I/O, It's off to disk I go, to read or write a bit or byte. I/O, I/O, I/O" Came across that one today :smile:

Hello, I was able to solve this problem fine, but I had a question about it: "A disk 8.00 cm in radius rotates at a constant rate of 1200 rev/min about its central axis. Determine (a) its angular speed, (b) the tangential speed at a point 3.00 cm from its center, (c) the radial...

I have four partitions, two of Windows and two of Linux. The Windows partitions have sizes 129 GB - C drive and 4 GB - W drive. When I check the amount of used space on C drive directly by right clicking on the C drive icon and then clicking properties, I get 55.1 GB used space and 74.1 GB...

Suppose I take a disk with a pie-sliced section cut out of it \] \unitlength 1mm \begin{picture}(90,90)(0,0) \linethickness{0.3mm} \multiput(20.75,77.28)(0.13,0.12){29}{\line(1,0){0.13}} \multiput(17.56,73.41)(0.12,0.14){27}{\line(0,1){0.14}}...

Hello, I am wondering what the best (and simplest) way to secure a rotor disk to a shaft is. I have a 3" diameter Acrylic disk with a 0.375" hole drilled in it to accept a 0.375" diameter steel shaft. What do you all think? Thanks, Jason O

I'm getting a rather crazy looking result, but I'm beginning to think it may be right. Unfortunately, I haven't been able to find any specific references on the topic to check my sanity level. Basically, I'm finding that in relativistic terms, there are no pressure (or tension) terms in the...

Last question I promise,,,, A uniformly charged disk has a radius of 2.5 cm and carries a total charge of 4*10^-12C. Find the electric field on the x-axis at a distance of 20cm away. I used the equation: Ex = (sigma/ (2*Eo)) * (1 - ( 1/ sqrt( ( R^2/x^2) + 1)) this is what i...

I'm somewhat clueless on how to solve the following problem, since a solid disk is rolling up a hill rather than downhill. I tried using KEi + PEi = KEf + PEf, including both KEt and KEr in KEf, and I calculated that KEi = 135J (45J are KEr, and 90J are KEt). I'm not sure if I'm plugging in...

this is my problem and it has a twist: find the electric field of a uniform disk of charge (assuming it's lying on the x, y plane) on a test charge located at the center of the disk on the z-axis but wait... here is the twist: displace the test charge a small displacement to the left. :eek...

(NOTE: I am doing this to possibly re-enter a graduate program and earn a PhD. This is not being done for class.) DJ Griffiths, Prob. 2.6, solved. My question is about the parallel component of the \vec{E}-field. If you integrate over cylindrical coordinates, then by symmetry this component...

As I understand it, it's all atomic material in the accretion disk of a big black hole, with very high orbital velocities and high density. However, the the disk is quite flat, and cooler than one would think with the velocities involved, because the material is swirling in smoothly, with...

A disk with a radial line painted on it is mounted on an axle perpendicular to it and running through its center. It is initially at rest, with the line at q0 = -90°. The disk then undergoes constant angular acceleration. After accelerating for 3.1 s, the reference line has been moved part way...

1. A solid disc of radius r, is rolling down a variable incline (a ramp). Show that the acceleration of the centre of mass, C is given by: a=g[ sinθ – F/Ncosθ ]. I have done this as shown below. N is the normal reaction and F is friction. N = mgcosθ F = µN = µmgcosθ mgsinθ – F = ma...

I am having a bit of trouble deriving the moment of inertia for a disk with uniform density: I=\int r^{2}\,dm=\int \rho r^{2}\,dV For a disk, I just used dA instead of dV. Now, to calculate the density: \rho = \frac{\text{mass}}{\text{volume}}=\frac{m}{\pi r^{2}} So now we have...

Ok, in my Physics 11 H class we did a lab with an inertial disk (a disk with a hub in the center, a string is attached to the hub like a huge half a yoyo where the yoyo is stationary and weights are the fingers falling down) and i need to be able to calculate the tension in the string for...

I am trying to reformat my hdd when something weird happened. I have a P4 desktop and I wanted to reinstall everything on there. So I booted from the windows CD and it formatted and installed windows XP sp1... when the computer restarted, it said that some file was missing and it wouldn't start...

Start Windows Explorer, right-click the computer's root hard disk, and then click Properties how do I find the computer's root hard disk in order to righ click on it?

If a hollow disk of say radius R is heated which causes it to expand a bit and a solid disk of radius slightly greater than R is fixed inside it after which both cool down, the solid disk will be in compression and the hollow disk in tension right? Now if this disk is rotated at a some speed...

Problem Sketch Okay so this is the problem the upper disk will be of M1 mass and R1 radius both disk are solid so I(oe)=1/2MR^2 , the second disk will be HM2 , HR2. After system is left from rest I understand that the lower disc will start rotating and going down from the rope also it has...

A uniform circular disk has radius 35 cm and mass 350 g and its center is at the origin. Then a circular hole of radius 11.667 cm is cut out of it. The center of the hole is a distance 17.5005 cm from the center of the disk. Find the moment of inertia of the modified disk about the origin...

Please could someone check my answers to the following and advise me on any of the bits I'm stuck on. Thanks ===== Q. A disk of radius a and mass m is suspended at its centre by a vertical torsion wire which exerts a couple \fontsize{5} -c\theta on the disk when it is twisted through an...

Just a quickie I'm taking a slice of a galaxy picture and plotting luminosity vs kpc. I'm fitting a luminosity profile (de vacouleurs) and keeping disk scale length as a free parameter. However, textual values for this (referred to as h from now on) range between 3-4 kpc for most galaxies. h...

Any help would be great Show that the centre of the mass of a uniform circular disk of radius, R, is at a point (4/3pi)R from the centre of the circle.

I am interested in conducting an experiment to prove or disprove the unusual qualities cited by many concerning the Faraday Disk generator. I have read from several different sources (some bias and others non bias) that an induced EMF can be measured while rotating an induction disk inside...

I already posted this somewhere, but silly me, i can't find it. Q: A disk of radius 2.40 cm and mass 1 kg is pulled by a string wrapped around its circumference with a constant force of 0.36 Newtons. What is the angular velocity of the disk to three decimal places after it has been turned...

Q: A disk of radius 2.40 cm and mass 1 kg is pulled by a string wrapped around its circumference with a constant force of 0.36 Newtons. What is the angular velocity of the disk to three decimal places after it has been turned through 0.85 of a revolution? So I started by obtaining my degrees...

So I've been using: \alpha=\tau/I More specifically: \alpha=(r*F)/(.5mr^2) I know I'm getting the acceleration just fine. I've then been using: \omega^2 = 2\alpha\Delta\Theta I know the problem is coming in here. Probably in conversion of units (rad/s^2) to (rev/s^2) or something...

My problem: A grindstone in the shape of a solid disk with diameter=0.480m and a mass of m=50.0kg is rotating at omega = 820rev/min. You press an ax against the rim with a normal force of F=190N View Figure , and the grindstone comes to rest in 8.00s. I need to find the coefficient of...

A computer disk is 8.0cm in diameter. a refrence dot on the edge of the disk is initially located at theta= 45 degrees. The disk accelerates steadily for 1/2 second, reaching 2000 rpm, then coasts at steady angular velocity for 1/2 second. what is the speed of the refrence dot at 1...

I'm curious, when am I supposed to use Washer, Shell or Disk method when trying to answer questions involving integrals and volume? Is there something specific I should look out for? I just can't tell the difference. Any help is appreciated. Thanks.

A disk of radius 1.4 cm has a surface charge density of 4.9 µC/m2 on its upper face. What is the magnitude of the electric field produced by the disk at a point on its central axis at distance z = 12 cm from the disk? I tried solving this problem in the same way you would solve a similar...

I have a diagram for this at http://snipurl.com/diagr There is a uniform disk with radius R, mass M, it has a string wrapped around it and is attached to a fixed rod. Part 1: Show the tension in the string is 1/3 the weight of the disk what i have done for this is Torque=Fd and...

hi, a friend is heading over to malaysia in the next few days and asked me if i wanted a 10000rpm ( 8mb cache, SATA ) 74 GB WESTERN DIGITAL 10000RPM hard disk. i would say yes but i am not sure if it will work on my pc my motherboard is an ASUS P4P800SE with Intel 865PE Chipset can someone...

Let me first start by saying that this problem is a challenge problem and the due date has passed (friday). I've still been working on it because it stumped me. in my physics class we did some integration based inertia problems. my calculus isn't all that great so its a bit tough for me...

/k. A disk of mass 15 kg and radius 25 cm is rotating initially at 20 rad/s. A constant force of 40 N is applied tangentially to it's edge, positively accelerating the disk. a) At t= 5 seconds, calculate the- 1) rotational velocity of the disk 2) the instantaneous power supplied to...

A uniform disk of mass Mdisk = 4.4 kg and radius R = 0.28 m has a small block of mass mblock = 2.4 kg on its rim. It rotates about an axis a distance d = 0.18 m from its center intersecting the disk along the radius on which the block is situated...

A disk 8.0 cm in diameter is initially at rest. A small dot is painted on the edge of the disk. The disk accelerates at 600rad/s^2 for .5s, then coasts at a steady angular velocity for another .5s. What is the speed of the dot at t = 1 s? Through how many revolutions has it turned? I...

Okay, so I'm having problems figuring out how exactly i can map the interior of Cassini's oval (|z^2-a^2|<r^2 , 0<a<r) onto the unit disk (|w|<1), so that the axis of symmetry are preserved. Anyone know how to do this? :confused: (In this case, the cassini oval is a peanut shaped domain, i think)