What is Bead: Definition and 133 Discussions

A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood or pearl and with a small hole for threading or stringing. Beads range in size from under 1 millimetre (0.039 in) to over 1 centimetre (0.39 in) in diameter. A pair of beads made from Nassarius sea snail shells, approximately 100,000 years old, are thought to be the earliest known examples of jewellery. Beadwork is the art or craft of making things with beads. Beads can be woven together with specialized thread, strung onto thread or soft, flexible wire, or adhered to a surface (e.g. fabric, clay).

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  1. P

    How Does a Charged Bead Behave in a Capacitor?

    Homework Statement A small bead of mass m= 34 g and charge of Q=140 mC has a velocity (all in the horizontal direction) of 7 m/s as it enters the gap of a parallel plate capacitor, initially traveling parallel to the plates. The plates are separated by 4 mm. If the bead enters the capacitor...
  2. N

    What is the Lagrangian and equation of motion for a bead on a rotating coil?

    Homework Statement A bead of mass m is threaded around a smooth spiral wire and slides downwards without friction due to gravity. The z-axis points upwards vertically. Suppose the spiral wire is rotated about the z-axis with a fixed angular velocity \Omega. Determine the Lagrangian and the...
  3. Saitama

    Understanding the Motion of a Bead on a Rotating Rod

    Homework Statement A bead of mass m slides without friction on a rod that is made to rotate at a constant angular velocity ##\omega##. Neglect gravity. a. Show that ##r=r_0e^{\omega t}## is a possible motion of the bead, where ##r_0## is the initial distance of the bead from the pivot...
  4. L

    Understanding Centripetal Forces on a Rotating Bead Hoop

    We have a bead confined on a circular hoop. The hoop is rotating around an axis tangential to it. Suppose the bead is intially at the point, farthest away from the axis, and has got some intial velocity. I have a question - in the frame of the hoop, there is a Coriolis force perpendicular to...
  5. C

    Bead sliding on a rotating rod Lagrangian

    Homework Statement A bead of mass m slides under gravity on a smooth rod of length l which is inclined at a constant angle ##\alpha## to the downward vertical and made to rotate at angular velocity ##\omega## about a vertical axis. The displacement of the bead along the rod is r(t)...
  6. H

    Bead on a wire, potential energy

    Homework Statement A particle is constrained to move without friction on a circular wire rotating with constant speed ω about a vertical diameter. Find the equilibrium position of the particle, and calculate the frequency of small oscillations around this position. Find and interpret...
  7. D

    Lagrangian Mechanics, bead on a hoop

    Homework Statement This is the problem: http://i.imgur.com/OJyzfhz.png?1 Homework Equations $$\frac{dL}{dq_i}-\frac{d}{dt}\frac{dL}{d\dot{q_i}}=0$$ $$ L=\frac{1}{2}mv^2-U(potential energy)$$ The Attempt at a Solution This is my attempt at question A): http://i.imgur.com/IeJVGm3.jpgDoes...
  8. S

    Bead on a loop in a non-inertial frame

    Homework Statement Consider a bead of mass m on a loop of radius R. The loop is rotating at a constant rate ω. Using a non-inertial frames of reference, find all equilibrium points of the bead on the loop. Homework Equations \vec{F_e}=m\vec{a_r}...
  9. C

    Particle Motion on Rotating Rod: Derivation and Special Cases

    Homework Statement A particle of mass m is free to slide on a thin rod. The rod rotates in a plane about one end at a constant angular velocity w. Show that the motion is given by r=Ae^(-γt)+Be^(γt), where γ is a constant which you must find and A and B are arbitrary constants. Neglect...
  10. I

    Understanding Work and Energy: A Short Guide

    Homework Statement http://postimage.org/image/sezpli4pv/ Having some difficulty understanding some concepts of Work and Energy. Homework Equations W = F * D KE = 1/2 mv^2 PE = mghThe Attempt at a Solution A) Speed is at B is less than the speed at D, because B has more PE than D B) False...
  11. L

    Ferrite Bead Usage: How Much Is Too Much?

    How much is too much, when it comes to using ferrites. Some of the boards I designed previously did not even have single ferrite. We pretty much never used ferrites. Compliance was not a problem. Now I design ARM9 based embedded system boards. There are ferrites for everything - NAND, DDR...
  12. P

    Bead sliding down a smooth cord.

    Hello, Homework Statement I am asked to show that the time it would take a bead to slide down a smooth cord, positioned at an angle beta wrt the vertical axis, is independent on that angle (between the cord and the axis). The bead starts its slide from rest. Homework Equations The...
  13. beowulf.geata

    Bead attached to a spring and moving along a horizontal wire

    I'm self-studying an introductory book on mathematical methods and models and came across the following problem: 1. A bead of mass m is threaded onto a frictionless horizontal wire. The bead is attached to a model spring of stiffness k and natural length l0, whose other end is fixed to a...
  14. T

    What is the angle of equilibrium for a spinning bead constrained to a hoop?

    Homework Statement A bead of mass m is constrained to move on a hoop of radius R which is spinning with angular velocity ω. There is no friction. Determine the angle θ at which the bead does not move for angular velocity ω. Do not consider the solution θ = 0. Homework Equations...
  15. M

    Bead on a Rotating Hoop - Constraints (Holonomic / Nonholonomic)

    1. Homework Statement We have a bead sliding with friction on a hoop oriented vertically. First the hoop rotates about its center with rotation axis perpendicular to its plane. Second, the hoop rotates about a vertical axis as well. In both of these cases, are the constraints holonomic or...
  16. D

    Lagrangian for Applied Torque on a Hoop with Bead

    Homework Statement I included the problem as an attachment. My difficulty lies within understanding how to account for the applied torque within the Lagrangian and subsequent Euler-Lagrange equations, which is what I want to use to determine the equations of motion of the bead on the hoop...
  17. B

    Bead on a rotating wire - holonomic or not?

    Homework Statement We have a bead sliding on a frictionless hoop oriented vertically. First the hoop rotates about its center with rotation axis perpendicular to its plane. Second, the hoop rotates about a vertical axis as well. In both of these cases, are the constraints holonomic or...
  18. B

    How does a lithium boarte bead stabilize itself after xrf excitation?

    My probelms is thus: I have a numerous samples that my company runs and I am trying to figure out how the lithium borate fusion of samples like silicon dioxide or Fe-Ti stabilize after excitation from xray to fluores. Becasue the way I would think is that the smaple/LiT is stable before...
  19. jfy4

    Bead and hoop in 2D using Lagrange

    Homework Statement A particle of mass m is placed on top of a vertical hoop of radius R and mass M. The particle is free slide on the outside of the hoop without friction while the hoop is free to roll in a vertical place without slipping. Use the method of Lagrange multipliers to determine...
  20. A

    Bead on wire tilted at angle theta.

    Homework Statement Consider a bead of mass m constrained to slide without friction along a rigid wire that rotates about the vertical at a fixed angle \theta with constant angular velocity \omega. Write down the Lagrangian in terms of z as the general coordinate. Find the equation of motion...
  21. F

    Bead sliding on a rigid straight wire

    Homework Statement A bead is free to slide along a rigid, straight wire, whilst the wire is rotating at angular velocity ω about the z-axis and is tilted away from the z-axis at angle α. I have the equation of motion (EOM) and need to find an explicit solution for the distance of the bead along...
  22. Z

    What factors affect the motion of a bead on a spinning hoop?

    A bead of mass m can slide on a frictionless circular hoop in the vertical plane with radius R. When the hoop spins around the vertical axis with a rate of ω, the bead moves up the hoop by an angle θ which depends on the angular velocity of the hoop. (Pic attached) a) Find θ in terms of ω, R...
  23. M

    A bead slides on a circular wire

    Homework Statement A bead slides on a smooth circular wire of radius b which lies in a vertical plane. The bead starts from rest at a point that is level with the center of the hoop. Find the time it takes for the bead to slide to the bottom of the hoop. The attempt at a solution at t=0...
  24. P

    Bead on the uniformly rotating wire

    "bead sliding on the uniformly rotating frictionless wire in free space" is the standard problem solved in Goldstein's classical mechanics book. The bead moves in outward direction (a=rω2) still why it is called as centripetal acceleration and not centrifugal?
  25. T

    Angular Momentum Eigenfunctions for Bead on a Wire

    Homework Statement A bead of mass m on a circular ring has the wave function Acos\stackrel{2}{}θ. Find expectation value, eigenfunctions & eigenvalues. Homework Equations The differential operator for the angular momentum is L = \hbar/i (\partial/\partialθ). The Attempt at a...
  26. P

    Motion of a bead on a rotating linear rod

    Homework Statement The center of a long frictionless rod, pivoted at the origin, is forced to rotate at a constant angular velocity Ω in the horizontal xy-plane. Write down the equation of motion for a bead threaded on the rod, using the coordinates x and y where x is measured along the rod...
  27. R

    Finding the Lagrangian of a bead sliding along a wire

    Homework Statement "A bead with mass m slides without friction on a wire which lies in a vertical plane near the earth. The wire lies in the x-z plane and is bent into a shape conforming to the parabola az = x2, where a is a positive known constant. (X is horizontal and z is vertical) The...
  28. L

    Classical mech non-inertial frame bead on a rotating ring

    Homework Statement Consider the bead threaded on a cicular hoop of example 7.6 (pg 260), working in a frame that rotates with the hoop. find the equation of motion of the bead, and check that your result agrees with eq 7. 69. Using a free body diagram explain the result 7.71 for...
  29. C

    Tension problem - bead sliding on a string attached to a pole

    Homework Statement A 100 g bead is free to slide along an 80 cm long piece of string ABC. The ends of the string are attached to a vertical pole at A and C, which are 40 cm apart. When the pole is rotated about its axis, AB becomes horizontal. Homework Equations F = ma...
  30. T

    Bead on wire with constant velocity

    Homework Statement A bead, under the influence of gravity, slides along a frictionless wire whose height is given by the function y(x). Assume that at position (x,y) = (0,0), the wire is horizontal and the bead passes this point with a given speed v0 to the right. What should the shape of the...
  31. rude man

    Feynman exercises bead parabola accelerometer

    In the subject accelerometer (see link) the answer given is a = kgx. I get a = 2kgx. I'm wondering if anyone cares to discuss this problem. The answerer used an energy argument that I'm not sure I followed, whereas I used a simpler force-balance method. F = force on bead by parabola and is...
  32. C

    Bead on a hoop, angular momentum

    http://img714.imageshack.us/img714/848/beadt.jpg In the above problem, the hoop will gain angular momentum, L, in the +y direction. However, initially the bead is on the bottom of the circle where the slope is exactly zero. The angular momentum will therefore point exactly upward (thus the net...
  33. S

    Analyzing a Rotating Rod with a Sliding Bead

    Homework Statement A small bead of mass m is free to slide along a long, thin rod without any friction. The rod rotates in a horizontal plane about a vertical axis passing through its end at a constant rate of f revolutions per second. Show that the displacement of the bead as a function of...
  34. beyondlight

    Speed and Normal Force of a Bead on a Loop-the-Loop

    A bead slides without friction around a loop-the-loop. The bead is released from rest at h=3,5R. a) What is the speed at point A? b) How large is the normal force at point A if its mass is m=5g?------------------------------------------------------- My question for: a) Do we consider the...
  35. K

    Bead on a vertical ring centripetal acceleration

    Homework Statement There is a vertical ring with a bead strung on it. The vertical ring spins at 4 revolutions per second, and the the bead moves up the ring at what angle from the bottom of the ring will the bead be at equilibrium? Is it possible for the bead to make it all the way up to the...
  36. AlexChandler

    Bead Parabola Accelerometer

    Homework Statement An accelerometer is made of a piece of wire with a bead on it that can slide on the wire with no friction. The wire is formed as a parabola y = kx2, as shown in the drawing. The bead rests at the lowest point of the parabola when it is at rest. When accelerated parallel to...
  37. M

    Bead on a titled wire, connected to a spring

    Homework Statement This is for a third year Nonlinear ODE and Chaos course, but the question at hand is a first year physics question. If this post belongs somewhere else, please let me know. "Consider the bead on a tilted wire, described below. Find the (equilibrium) equation from...
  38. A

    Ferrite bead as low pass filter search

    Hi i'm looking for a ferrite bead that will block 1-20 Mhz frequancies and pass all lower ones is it possible ? can someone to advice me for one specific? Arye
  39. S

    Circular motion of bead and wire

    Homework Statement A bead threaded on a frictionless vertical wire hoop of radius R. The hoop rotates about a vertical axis through its center. Period of revolution of the hoop is T. The bead has a mass m. Find the normal force N exerted on the bead by the wire.Homework Equations Fc=mv^2/r The...
  40. Z

    Which bead arrives first at the finish: A or B on a curved wire?

    I have been working on this for a few days and can't seem to find the right direction to go in. Here's the problem: Two beads, A and B, slide along frictionless wires. Bead A moves along a straight horizontal wire. Bead B moves along a wire with a dip in it, but it returns to its...
  41. M

    Does the Bead's Speed Change as It Slides Along a Frictionless Curve?

    Homework Statement The figure below shows a bead sliding without friction along a curved wire in a vertical plane. IMAGE: http://img545.imageshack.us/i/bead.png/ The bead slides starting from rest at position B on the frictionless wire. The direction of the gravitational field is in the...
  42. P

    The Bead on a Vertical Ring: Finding Acceleration

    Homework Statement A bead rests on smooth vertical ring of radius R. Bead is given a slight push so that it slides down around the ring. At some instance the bead is at angular position θ with vertical then choose correct option from the following A. acceleration of bead is vertical at θ =...
  43. B

    Solve Bead Problem: Find Height & Angle for 4.5m/s Velocity

    Homework Statement Homework Statement [/b] Situation: bead sliding on a fristionless wire. How large must the hieght be if the bead starting at rest is to have a velocity of 4.5m/s at the lower point? What angle will give the shortest time to achieve the correct velocity? Homework...
  44. I

    Bead on a rotating vertical ring

    Hi I have some conceptual questions about one situation. I have posted the picture. We have a bead on a ring which is rotating about the vertical axis passing through its center. The bead is not tied to the center of the ring , though it appears like that in the figure. Let m be the mass of...
  45. A

    Bead sliding on a rotating straight rigid wire.

    Homework Statement I think I will start with the figure below: The wire of infinite length rotates about the point "a" with constant angular speed. The bead starts out at rest. There is no friction or gravity. I have already derived the equations of motion for this system (I used...
  46. M

    Bead on loop of wire in rotating frame

    Homework Statement Consider a bead sliding without friction on a circular hoop of wire rotating at constant \Omega, where \phi is the angle between the bottom of the hoop and the bead. Find the equation of motion of the bead. \hat{\Omega}=\hat{z} Homework Equations...
  47. V

    I am looking into calculating the weld bead strength. I am unsure of

    I am looking into calculating the weld bead strength. I am unsure of calculating the shear stress..the attachment has a drawing..any help is appreciated
  48. M

    Bead on straight wire that rotates around origin

    Question: A Particle of mass m can slide freely along a straight wire placed in the x-y plane whose perpendicular distance to the origin O is h. Denote the projection of O on the wire by on the wire by C. The line OC rotates around the origin (in the x-y plane) at a constant angular velocity...
  49. P

    Bead on a hoop+accelerating elevator

    Homework Statement http://img839.imageshack.us/img839/8904/bead.jpg Uploaded with ImageShack.us The picture speaks for itself. I'm asked to find the minimum velocty that this bead should be given so that it will reach point B. 2. The attempt at a solution I've solved this question using...
  50. D

    Why Ferrite Bead in Supply line

    Presently Am try to design a USB to UART,485& 232 board, in that Am using FTDI USB to UART converter, In the FTDI data sheet they providing some sample design and A ferrite bead is connected in series with the USB power supply to reduce EMI noise from the FT232R and associated circuitry being...
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