What is Turntable: Definition and 103 Discussions

A phonograph, in its later forms also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or since the 1940s called a record player, is a device for the mechanical recording and reproduction of sound. The sound vibration waveforms are recorded as corresponding physical deviations of a spiral groove engraved, etched, incised, or impressed into the surface of a rotating cylinder or disc, called a "record". To recreate the sound, the surface is similarly rotated while a playback stylus traces the groove and is therefore vibrated by it, very faintly reproducing the recorded sound. In early acoustic phonographs, the stylus vibrated a diaphragm which produced sound waves which were coupled to the open air through a flaring horn, or directly to the listener's ears through stethoscope-type earphones.
The phonograph was invented in 1877 by Thomas Edison. Alexander Graham Bell's Volta Laboratory made several improvements in the 1880s and introduced the graphophone, including the use of wax-coated cardboard cylinders and a cutting stylus that moved from side to side in a zigzag groove around the record. In the 1890s, Emile Berliner initiated the transition from phonograph cylinders to flat discs with a spiral groove running from the periphery to near the center, coining the term gramophone for disc record players, which is predominantly used in many languages. Later improvements through the years included modifications to the turntable and its drive system, the stylus or needle, and the sound and equalization systems.
The disc phonograph record was the dominant audio recording format throughout most of the 20th century. In the 1980s, phonograph use on a standard record player declined sharply due to the rise of the cassette tape, compact disc, and other digital recording formats. However, records are still a favorite format for some audiophiles, DJs, collectors, and turntablists (particularly in hip hop and electronic dance music), and have undergone a revival since the 2000s.

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  1. mapika123

    Power calculations for a motor spinning a turntable

    Hi, I have a 1 HP motor spinning a turntable (just a wheel) weighing 1kg, diameter 25cm speed 2000rpm. (Arbitrary specs). If I have to spin a turntable with the same weight (1kg) but double the diameter (50cm) at the same speed, would I necessarily need a motor with double the power (2 HP)...
  2. runningman19

    Good Bearing for a Low Friction Turntable?

    Hi Everyone, I am working on a project which involves building an extremely low friction turntable. To give you an idea of how low, we're placing a tank full of water on top of the turntable, placing a stirrer into the tank, turning the stirrer on and trying to get the tank to rotate on the...
  3. N

    Coin on a turntable problem in a noninertial frame

    1. The problem statement A small coin of mass m is placed on a turntable a distance a from the axis. Imagine that the surface is a little sticky, so the coin does not slide immediately. The turntable (initially at rest) is rotated at constant angular acceleration α, beginning at t=0. a.) Find...
  4. M

    Angular momentum with a large wooden turntable

    Homework Statement Homework Equations Li = Lf L = I*omega K = (1/2)*(I)*(omega)^2 The Attempt at a Solution [/B] Given that there are no non-conservative forces in action, I am assuming that the two kinetic energies should be equal. However, as shown by my work above, the two values...
  5. R

    Calculate the magnitude of angular acceleration

    Homework Statement A record player rotates normally at a rate of 18 rev/m. It takes 70 seconds for it to slow down to a stop when you turn it off. Homework Equations Calculate the magnitude of its angular acceleration. The Attempt at a Solution answer key says the correct answer should be...
  6. anon11

    Ball on a Turntable Simple Harmonic Motion

    Homework Statement A spherical ball of mass “m”, moment of inertia “I” about any axis through its center, and radius “a”, rolls without slipping and without dissipation on a horizontal turntable (of radius “r”) describe the balls motion in terms of (x,y) for a function of time. **The...
  7. anon11

    Ball Rolling Without Slipping On A Turntable

    Can someone please help me out with this tough problem? 1. Homework Statement A ball rolls on a turntable without slipping describe the balls motion in terms of (x,y) for a function of time. (The turntable spins at a constant rate) (This all the information that the professor gave us.)The...
  8. BrainMan

    Turntable Rotating on Shaft Problem

    Homework Statement Homework Equations ωf = ωo = αt ∑τ = Iα The Attempt at a Solution [/B] 1) Find the acceleration ωf = ωo + αt (ωf-ωo) / t = α = -0.231 rad/sec 2) Find ∑τ ∑τ =Iα I assumed that the only torque acting on the turntable was the torque due to friction τfriction =...
  9. D

    Bug moving on a turntable rotating with constant omega

    Homework Statement A cockroach crawls with constant speed in a circular path of radius b on a phonograph turntable rotating with constant angular speed omega. The circle path is concentric with the center of the turntable. If the mass of the insect is m and the coefficient of static friction...
  10. AndreewL

    Angular Momentum, Inertia and Kinetic Energy?

    Homework Statement A large wooden turntable in the shape of a flat disk has a radius of 1.50 m and a total mass of 100 kg. The turntable is initially rotating about its vertical axis through its centre with an angular velocity of 2.50 rad/s. From a very small height a 100 kg sand bag is...
  11. R

    Calculating Final Angular Velocity of Turntable with Runner on a Horizontal Axis

    Homework Statement A 55 kg runner runs around the edge of a horizontal turntable mounted on a vertical, frictionless axis through its center. The runner's velocity relative to the Earth has magnitude of 3.1 m/s. The turntable is rotating in the opposite direction with an angular velocity of...
  12. T

    Physics of a microwave - why does the turntable spin?

    Homework Statement A microwave oven operates by injecting electromagnetic waves with a frequency of 2.45 GHz into the cavity formed by the conducting metal shields on each face of the oven box. Explain, with the aid of sketches and simple calculations, why it is generally necessary to rotate...
  13. J

    Radial acceleration of a particle in a groove on a turntable

    Homework Statement A horizontal turntable rotates at a constant rate ω about a fixed vertical axis through its center O. A particle of mass m can slide in a fictionless circular groove of radius r centered at O' which is r/3 from O. What is the radial acceleration of m in direction O'm...
  14. Anthony.404

    What is the recommended electric motor power for turning a railway turntable?

    Me and my friend are working on an old railway turntable for a museum, but we run into some problems. We need to know the force we needed to turn it with an electric motor, after spending a week trying with angular momentum we hit a dead end. The train that going to use the turn table wegint...
  15. Z

    Centripetal acceleration turntable problem

    Homework Statement A small container of water is placed on a turntable inside a microwave oven, at a radius of 12.0 cm from the center. The turntable rotates steadily, turning one revolution in each 7.25 s. What angle does the water surface make with the horizontal? Homework Equations F = ma a...
  16. A

    Harry Potter's Physics on a Rotating Turntable

    Homework Statement A turntable with I=400 kgm2/s and radius 2m is rotating at omega=2 rad/s. Harry Potter (HP) of mass 60 kg and Tri-Wizard Cup (TWC) of mass 20 kg are diametrically opposite to each other on the rim of the turntable. a) What is HP's tangential velocity? b) HP falls off...
  17. C

    Mass on a slope on a turntable

    Homework Statement A wedge with face inclined at an angle theta to the horizontal is fixed on a rotating turntable. A block of mass m rests on the inclined plane and the coefficient of static friction between the block and the wedge is μ. The block is to remain at position R from the centre of...
  18. N

    Solving Turntable Coin Problem: Angular & Linear Accelerations

    A very small coin is at distance 10.5 cm from the spindle of a turntable. The turntable starts spinning from rest with constant angular acceleration. In 0.133 s the coin's centripetal acceleration is 1.39 times its tangential acceleration. 1)Find the turntable's angular acceleration. 2)Find the...
  19. T

    Rotation with a turntable

    I know this is not typical and you aren't suppose to solve the problem for the person just give hints, however my teacher has not taught this and expects us to know it. For whatever I cannot grasp how to do this any help would be great thank you! 1. Homework Statement The turntable of a...
  20. B

    Angular Acceleration of a Wheel on a Turntable

    Homework Statement [/B] The axle of a wheel is mounted on supports that rest on a rotating turntable. the wheel has angular velocity ##\omega_1 = 44.0\; \frac{\textrm{rad}}{\textrm{s}}## about its axle, and the turntable has angular velocity ##\omega_2 = 35.0\; \frac{\textrm{rad}}{\textrm{s}}##...
  21. L

    Rotation angular velocity of a turntable

    I've spent at least an hour trying to figure this out, but can't seem to figure out how to solve this. 1. Homework Statement A 170g , 30.0-cm-diameter turntable rotates on frictionless bearings at 66.0rpm . A 25.0g block sits at the center of the turntable. A compressed spring shoots the block...
  22. Z

    Rotational Kinematics of a turntable

    Good afternoon! I've been mulling over this question for a bit and I can't seem to understand what it is asking. This is a question for an introductory calculus-based physics university course. 1. The Problem: A uniform disk, such as a record turntable, turns 8.0 rev/s around a frictionless...
  23. S

    Circular Motion of a turntable

    Homework Statement A turntable rotates counterclockwise at 78rpm, a speck of dust on the turntable is at 0.42rad at t=0 ,What is the angle of the speck at t = 8.0s ? Your answer should be between 0 and 2π rad Express your answer using two significant figures.Homework Equations θf-θi=ωt The...
  24. G

    Balancer moving on a turntable

    Hi. The problem is the following: We have a balancer initially at the end of a plank that spins around an axis at its center. The initial rotation period is T_{0}. The balancer starts to walk with constant speed along the plank and we are asked to answer some questions about it. a) What...
  25. P

    Why Does a Coin Fly Off a Turntable?

    If I put a coin on a turntable at some distance away from the center and start turning the turntable eventually there will be a speed where the coin will fly off from the turntable. If we put this into calculation. We will equate the centripetal force and static friction to find out the...
  26. V

    Angular momentum of turntable problem

    Homework Statement A 1.9kg , 20 cm-diameter turntable rotates at 150rpm on frictionless bearings. Two 480g blocks fall from above, hit the turntable simultaneously at opposite ends of a diameter, and stick. what is the objects angular velocity in rpm right after this event? Homework...
  27. D

    Max Rotation Rate of a Slowing Turntable

    Homework Statement A turntable of radius "r" is spinning counterclockwise at an initial rate of ω. at t=0, its rotation rate begins to slow at a steady pace. the rotation finally stops at t=T. At what time is ωt^2 maximum. Express your answer in terms of T.
  28. D

    Circular Motion of a turntable spinning counterclockwise

    Homework Statement A turntable of radius "r" is spinning counterclockwise at an initial rate of ω. at t=0, its rotation rate begins to slow at a steady pace. the rotation finally stops at t=T. At what time during the time interval 0<t<T was the magnitude of the centripetal acceleration of a...
  29. P

    Angular momentum; turntable problem

    Homework Statement A 1.7 kg , 20cm--diameter turntable rotates at 140rpm on frictionless bearings. Two 480g blocks fall from above, hit the turntable simultaneously at opposite ends of a diameter, and stick. What is the turntable's angular velocity, in rpm , just after this event...
  30. T

    Turntable Problem: Homework Solution

    Homework Statement A large turntable of radius 6 m and moment of inertia I = 500 kg m^2 about its center is rotating with an angular velocity of 1 radian/s. A girl of mass 30 kg standing at the exact center moves slowly outward to the edge of the turntable. a) What is the angular...
  31. R

    The angular speed of the turntable with a woman on it? Help

    The angular speed of the turntable with a woman on it? Help! Ok so I understand part a (why it's counterclockwise. τ = Fr = (mg)(2) = (70)(9.8)(2) = +1372) Part b is where I'm stuck... This is what I did... PEinitial + KEinitial rotational = PEfinal + KEfinal rotational PEinitial =...
  32. J

    Centripital Force Turntable (record player)

    Homework Statement This is not a homework question, just a problem I want help solving. Don't be afraid of giving too much of the answer, I am not even in a physics course right now. When setting up a turntable/record player, you need to dial in an "antiskate force". This is an outward...
  33. T

    Motion of a particle on a rotating frictionless turntable

    Homework Statement 1 A particle is gently placed on a frictionless rotating turntable at a distance r from the centre.Describe particle motion from both ground and table frame. 2 A particle is at a distance r from the centre of a frictionless stationary turntable.The turntable then starts...
  34. M

    Need to support horizontal spinning tire: turntable or thrust bearings?

    Hi everyone. I need to create a mechanism involving a 12" diameter horizontal tire, spinning at 3000RPM, with 2kg mass. The wheel will be attached to a spinning shaft. The only thing, I need to support the wheel from the bottom using flat bearings of some sort, so it can spin freely...
  35. T

    Mouse onto the edge of phonograph turntable

    Homework Statement mmouse = 0.06kg r = 0.3m \omega = 0.05 rad / s Suppose angular speed does not change. What is the work needed for the mouse to go to the center. Homework Equations Io\omegao = If\omegaf The Attempt at a Solution If \omega doesn't change ,then how can...
  36. J

    Conservation of Angular Momentum of Turntable Problem

    Homework Statement A turntable with moment of inertia of 2.0kg*m^2 has a radius of 0.80m and an angular velocity of 1.5 rad/s. A ball is thrown horizontally of 0.4kg at 3.0 m/s and is caught by the turntable by a small and very light cup-shaped mechanism at the turntable's edge. What is the...
  37. C

    Rotational kinematics of a turntable

    Homework Statement An electric turntable 0.710 m in diameter is rotating about a fixed axis with an initial angular velocity of 0.230 rev/s. The angular acceleration is 0.887 rev/s^2. A. Compute the angular velocity after a time of 0.192 s. B. Through how many revolutions has the blade...
  38. S

    Motion in a plane II, Coin on a turntable with Vmax

    Homework Statement A 3.90 g coin is placed 12.0cm from the center of a turntable. The coin has static and kinetic coefficients of friction with the turntable surface of Ws= 0.800 and Wk= 0.410. What is the maximum angular velocity with which the turntable can spin without the coin...
  39. P

    HELP ME PLEASE: A flea is at point A on a horizontal turntable

    A flea is at point A on a horizontal turntable 8.1 cm from the center. The turntable is rotating at 33.9 rev/min in the counterclockwise direction. The flea jumps vertically upward to a height of 4.11 cm and lands on the turntable at point B. Place the coordinate origin at the center of the...
  40. A

    Motion in accel. frames - water in turntable

    Homework Statement A small container of water is placed on a carousel inside a microwave oven, at a radius of 12.0 cm from the center. The turntable rotates steadily, turning through one revolution in each 7.25 s. What angle does the water surface make with the horizontal? Homework...
  41. N

    Best way to approach this see saw on a turntable?

    Hi forumers! I have a concept for a DSLR boom crane and I want to operate it using stepper motors via belts/gears or pulleys. It will be mounted on a driven turntable bearing on a tripod. The boom acts like a see-saw when mounted on the turntable. The load distance from the apex of the...
  42. J

    Coefficient of Static Friction on a Turntable

    I'm doing a lab for my technical dynamics class and that lab is to determine the coefficient of static friction between a metal washer and both metal and rubber surfaces. I did the experiment using 3 washers set at different distances from the center of the turntable as instructed, and...
  43. A

    Calculating Coefficient of Friction for a Coin on a Turntable

    I've got the answer to the problem but I'm one decimal place off from the back of the book and am suspecting a typo (no, lol... not that presumptuous...) the reason for the suspicion is that there's a zero after the answer where the units would go but this question is asking for a coefficient...
  44. B

    Mass on a rotating turntable problem.

    [PLAIN]http://img841.imageshack.us/img841/7913/314pw.jpg I'm having a bit of trouble with this one. So the FBD of the block. In the y coordinates, the normal equals its weight in the x coordinates, we have static friction to the left, and is there a force to the right? There as to...
  45. D

    Angular Momentum (Not the usual Turntable Question)

    Homework Statement A dog of mass m is standing on the edge of a stationary horizontal turntable of totational inertia I and radius R. The dog walks once around the circumference of the turntable. What fraction of a full circle does the dog's motion make with respect to the ground? Express...
  46. R

    Moment of Inertia of a turntable

    Homework Statement A uniform circular turntable of mass 2m and radius R is at rest in space. Koko throws a lump of putty of mass m and speed v toward the edge of the turntable so that it sticks at the extreme edge of the turntable at R. Using conservation of L, show that the angular...
  47. I

    Friction force, what causes it? Unslipping coin on spinning turntable w/ constant vel

    Homework Statement A coin is off-center on a turntable which is spinning at a constant velocity. The coin is not slipping. From what I have gathered, the radial acceleration of the coin is caused by the force of static friction on the coin. There is no tangential acceleration. Homework...
  48. M

    Rotational motion of a turntable

    Homework Statement The turntable of a record player rotates at 33.33rev/min and takes 20.0s to reach this speed from rest. Calculate: a) its angular acceleration, b) the number of revolutions it makes before reaching its final speed. Homework Equations angular acceleration = angular...
  49. M

    What is the force of friction on a 50 gram coin on a turntable?

    Homework Statement A 50 gram coin is on a horz. turntable. it rides without slipping making 1 revolution every 1.8 seconds. it is 10 cm from the center. the coefficient of static are 1 and the coefficient of kinetic is 0.5. the size of the force of friction on the coin is Homework Equations...
  50. E

    Calculating the Resulting Speed of a Student on a Turntable

    Homework Statement A student of mass m=40 kg is standing on the edge of a uniform, frictionless turntable, with diameter d = 5m and mass M=400 kg. The student and the turntable are initially rotating counterclockwise together about a fixed axis through the center of the turntable with an...
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