What is Vibration: Definition and 471 Discussions

Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin vibrationem ("shaking, brandishing"). The oscillations may be periodic, such as the motion of a pendulum—or random, such as the movement of a tire on a gravel road.
Vibration can be desirable: for example, the motion of a tuning fork, the reed in a woodwind instrument or harmonica, a mobile phone, or the cone of a loudspeaker.
In many cases, however, vibration is undesirable, wasting energy and creating unwanted sound. For example, the vibrational motions of engines, electric motors, or any mechanical device in operation are typically unwanted. Such vibrations could be caused by imbalances in the rotating parts, uneven friction, or the meshing of gear teeth. Careful designs usually minimize unwanted vibrations.
The studies of sound and vibration are closely related. Sound, or pressure waves, are generated by vibrating structures (e.g. vocal cords); these pressure waves can also induce the vibration of structures (e.g. ear drum). Hence, attempts to reduce noise are often related to issues of vibration.

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  1. S

    What is the frequency of the car's vibration

    Having trouble figuring out these 4 problems. I could use a walk through or an answer. thanks guys. Homework Statement 1a)When four people with a combined mass of 270 kg sit down in a car, they find that the car drops 1.00 cm lower on its springs. Then they get out of the car and bounce it up...
  2. S

    Torsional Vibration Natural Frequency & Nodal Position

    Hi I was doing an exercise of calculating the "natural frequency" of a 3-mass system. The problem is like: A shaft has three inertia on it of 6, 4 and 10 kgm2, respectively viewed from left to right. The shaft connecting the first two is 2.6 m long with a stiffness of 12 x 106 Nm/radians...
  3. Z

    Vibration & Phonons in Solids: Notes & Resources

    I'm looking for some notes concerning the following areas: Vibration in solids, Phonons, Specific heat capacity of solids, Electron gaz in solids, Debye model, stuff like that, any help ?
  4. D

    Formula for Calculating vibration

    Hello, I am looking for calculating vibration, can anyone help me with formula David
  5. R

    Best Vibration Books for Asian Mechanical Engineering Students

    Hi everyone, I am an undergraduate student of Mechanical Engineering in Jakarta, Indonesia. I’ve found all of these Vibration books in my library: Vibration for Engineers, 2nd Ed. by Andrew Dimaragonas Prentice Hall An Introduction to Mechanical Vibrations, 3rd Ed. by Robert F...
  6. R

    Vibration and Waves: Springs

    Homework Statement For a mass m hung vertically from a spring with spring constant s, the restoring Force is F=-sx where x is the displacement from equilibrium. a)What are the periods of the two harmonic oscillators i) and ii). b)Assuming eaqch oscillator is moving with the same...
  7. S

    Difference between forced vibration and combined SHM

    what is the difference between forced vibration and combined SHM. since both include motion of particle under the influence of two periodic force
  8. H

    Vibration problem: mode shape?

    Hi all. I am taking a course in mechanical vibrations. I know that a mode shape is a pattern specific to a natural frequency of a system. That maens, the mode shape is determined under the context of free vibration, right? What kind of information can we obtained from the mode shape? Is the...
  9. N

    How Do You Measure Vibration Decay in Damped Drumsticks?

    Hi, I am currently in the process of completing my final year mechanical engineering thesis, which compares the dynamics of damped drumsticks (not the chicken ones, the drum kit playing ones!) with those of a conventional, undamped drum stick. I now am up to the point where I need to...
  10. C

    Superstrings - what happens when a string has no vibration?

    Can anyone tell me what would happen if a "string" (as in the strings in the superstring theory) for some reason had no vibration. Would it cease to exist? Would it just release all of its energy?
  11. B

    Frequency of Vibration for a Block Supported by Two Springs

    Homework Statement A block of mass m is supported by two identical parallel springs, each with spring stiffness constant k. What will be the frequency of vibration? Homework Equations f = 1/[2*pi*sqrt(m/k)] The Attempt at a Solution I am just curious how the fact that there are two springs...
  12. N

    Can Lightning Create a Sonic Boom?

    If two metal objects hit, do the objects have to vibrate to make a sound? Or can the air itself vibrate with the sound?
  13. G

    How Does Doubling Molecular Mass Affect Vibration Frequency?

    1. The mass of the deuterium molecule D2 is twice the mass of Hydrogen molecule H2. If the vibrational frequency of H2 is 1.35x10^14 Hz, what is the vibrational frequency of D2, assuming the "spring constant" of attracting forces is the same for two species? Answer in unit of Hz. Homework...
  14. D

    Vibration and Frequency Questions

    Homework Statement A 75 g bungee cord has an equilibrium length of 1.20 m. The cord is stretched to a length of 1.80 m, then vibrated at 20 Hz. This produces a standing wave with two antinodes. Homework Equations Linear Density = m/LThe Attempt at a Solution So far I've only found the linear...
  15. A

    How Does the Average Frequency (w1+w2)/2 Affect Undamped Forced Vibrations?

    as we know ,the equation to the undamped forced vibration is x=Asin{(w1+w2)/2}sin{(w1-w2)/2},the symbols have their usual meaning..but i can't understand how (w1+w2)/2 comes in picture in the phasor diagram...also its significance
  16. S

    The Impact of Vibration on Human Health

    gooooood evening.. i have presentation about the effect of vibration on human and i did not find what i want and i did not understant the topices when i searched from google .. so I will be grateful if anyone could help me..
  17. O

    Ideal Gas Assumption: No Vibration & Rotation

    Should there also be an assumption for ideal gaes that states: The gas molecules/atoms do not vibrate and rotate I was considering a case of a gas expanding at a dropping pressure such that the value of PV remains a constant. Work is done since there is an increase in volume. If there is...
  18. T

    Vibration, density and the aether

    I have had an idea now for a while and am just wondering if the direction along the path of thinking that I am using is followed in any well established theorys. The basis for my thoughts is that mass/particles are ultimately vibrations of that which the vaccume of space consists of...
  19. L

    String vibration and frequency,amplitude,length

    A string vibrates at its third-harmonic frequency. The amplitude at a point 30 cm from one end is half the maximum amplitude. How long is the string? i figured since the amplitude at point 30 cm is half the max amplitude, the amplitude must be at 60 cm. The third harmonic...
  20. B

    Atomic Vibration: Disproving the Theory

    Hello all, I'm having a little trouble researching this as I'm not sure what the exact field of study is called, googling Atomic Vibration doesn't come up with much. Basically I am looking to disprove a theory (with hard science) that thoughts can affect the crystalisation of water. The...
  21. D

    How can I test the frequency of a vibration

    For a project i want to see which viration dampeners would work most effiecently is there any way i could use some sort of invention other then an accelerometer to test this?
  22. D

    Physics of a Vibration Dampener (Tennis shock absorber)

    Can someone explain to me the physics involved in this? Why does the dampener absorb some of the shock? Where does that shock go? This sort of stuff... Please do explain Thanks in Advance
  23. A

    Molten Salt: Disassociation or Vibration?

    Generally, when you melt a salt (CaCl2 @800deg C specifically) are the ions disassociated as in a solution or is molecular vibration simply great enough to not allow the formation of intermolecular bonds and the atoms are floating around still paired? This is probably a dumb question and my...
  24. K

    World's largest guitar - frequency of vibration

    I have a problem on my sheet that is confusing me. The problem states The world's largest guitar, which was built by high school students in Indiana, has strings that are 9.0 long. The fundamental vibration that can be induced on each string has a wavelength equal to twice the string's length...
  25. N

    Vibration Free Table for Holograms

    Hello, I am interested in making a vibration free table to make holograms. The way I was going to do it was to put innertubes under the corners of a box. Then fill the box with sand. I will test it by putting components on the sand to make a interferometer. Are there better ways of doing this...
  26. I

    What frequency of vibration is required?

    Homework Statement (a) acceleration amplitude of 100 ms−2 with a vibration amplitude of 5.0 cm. (i) What frequency of vibration is required? (ii) What is the maximum speed ? (iii)What is the time delay between the points of maximum acceleration and of maximum speed? Homework...
  27. L

    Analysis of Vibration of Rod Clamped at Midpoint

    :confused: Hi guys,just performed the experiment using the kundt's tube.. I just can't understand why the rod is clamped at midpoint..hmmmmm,what's your analysis on the vibration of the rod clamped at midpoint... thanks in advance..:smile:
  28. N

    What will be the amplitude and frequency of vibration

    A fisherman’s scale stretches 2.8 cm when a 3.7 kg fish hangs from it. a. What is the spring constant, and b. What will be the amplitude and frequency of vibration of the fish is pulled down 2.5 cm more and released so that it vibrates up and down? a) F=ma F=(3.7 kg)(...
  29. M

    Simple Harmonic Motion and frequency of vibration

    When a 63 kg person climbs into a 1040 kg car, the car's springs compress vertically by 3.3 cm. What will be the frequency of vibration when the car hits a bump? Ignore damping. Here is the FBD I have drawn: http://img276.imageshack.us/img276/6189/fbdcc2.png Im not even sure if this is...
  30. D

    INTRO TO PHYSICS: Impedence, pitch, vibration, reasonance

    EASY STUFF: Impedence, pitch, vibration, reasonance... Please Help! I would really appreciate it if you guys could take a look at these problems I have difficulty with. Thanks a lot. My answers are in red. 1. As impedance decreases, frequency decreases? 2. For the vibration spectrum (of...
  31. D

    PHYSICS OF MUSIC: Pitch is organ pipes & vibration spectrum

    Hi. I would really appreciate it if someone could tell me whether I'm correct or not. :smile: 1. An open pipe (open at both ends) and a closed pipe (closed at one end) are the same length. If an organ blows air across the top of each pipe, what is true of the frequency (and pitch) of the...
  32. P

    Can Harmonic Vibration Explain the Forces of the Universe?

    Can anyone with a stronger math/physics backround than me prove/disprove this... Attractive and repelling forces which form molecular, and atomic structure (mass) do so because of "musical" harmonies between oscillations. AKA if you plot atomic vibrations as sine waves, do molecular...
  33. S

    What causes the vibration of one guitar string

    My friend brought up this concept somehow and I know the answer, I just CANT remember what it's called. Sounds silly, I know. But anyways perhaps someone here can help me. What causes the vibration of one guitar string to be the same frequency of another one that has been plucked on that...
  34. A

    Absorption of radiation at vibration frequency

    why is enerygy absorbed if the frequency of the radiation matches the frequency of the vibration?
  35. Amith2006

    Frequency of vibration of air column

    Sir, Consider a resonance column which is in unison with a tuning fork of particular frequency. Now by varying the length of the air column, resonance is obtained at different lengths. How is this possible? I have this doubt because each length of air column vibrates with a particular...
  36. J

    Does Mass Affect Vibration Response in Single Degree of Freedom Systems?

    Considering the free vibration response of a single degree of freedom system: It is observed ,that, larger the Time Period (Vibration Period -"T") of the system(consider a single degree of freedom system), greater is the peak deformation of the system.Right? Time Period on the other hand...
  37. J

    What Is the Difference Between Vibration and Oscillation?

    What is the difference between vibration and oscillation?
  38. G

    Investigating Vibration Reduction in Sheet Metal Using Electromagnetic Damping

    hello. can u help me with this planing execise manufacturers of sheet metal use rollers to produce the sheets. The sheets then pass along processing lines for painting. Transverse vibrations of these sheets results in a non uniform thickness of paint layers on the sheets. Electronmagnetic...
  39. C

    How do two-dimensional surfaces vibrate under forced oscillations?

    Hi, I'm looking into the subject of "Chladni plates": http://www.physics.montana.edu/demonstrations/video/3_oscillationandwaves/demos/chladniplates.html For a lecture I'm supposed to prepare, and I'm looking for information on how exactly a two-dimensional surface vibrates under forced...
  40. M

    Vibration Making: How Sander Mechanism Works

    I interest how can vibration be maked.That is,for example sander.how does the mechanism of the vibration sander functions?is there any idea?:uhh:
  41. L

    Stroboscope and string vibration

    I am a college student, currently in Physics II. Got a simple question. I didnt have time in lab / I forgot to do this part, and the lab report is due tomorrow. Our lab was on standing waves on a string. Using a string vibrating device, and a hanging mass on the other end to play with the...
  42. H

    Interpreting Vibration Magnification Factor Overestimation

    Hi all. (I've edited the question) As far as my intuition tells me, an underestimation of the damping effect would results in an overestimation of the magnification factor, am I correct? So I expect the experimental determined magnification factor for all frequency ratio to be smaller than the...
  43. H

    Need help with a torsional vibration problem

    [Urgent] Need help with a torsional vibration problem Hi all! I am doing a problem on torsional vibration as follow: "Two shafts A and B are geared togather such that the speed of B is 2.5 times that of the speed of A. The shaft A, of 50mm diammeter and 600mm length carries a wheel of moment...
  44. C

    Calculating Bullet Speed Before Impact for Vibration Problem

    A 20.0 g bullet strikes a 0.600 kg block attached to a fixed horizontal spring whose spring constant is 6.74 103 N/m and sets it into vibration with an amplitude of 21.2 cm. What was the speed of the bullet before impact if the two objects move together after impact? I've been stuck on this...
  45. P

    Vibration caused by spin fixtures?

    How would you go about trying to determine the vibration caused by a simple spin fixture and dyno for testing engine components. I am working on a project that involves attaching spin fixtures to a base plate for testing purposes. The question is how to have the base plates attached to the...
  46. T

    Discrete modes of vibration for sonometers

    Hi, I have a few questions about Sonometers which I've attempted to think through - though I may be missing something. Perhaps someone can fill in any gaps for me? If I was to be asked why only 'discrete modes' of vibration can exist for a sonometer, is it enough merely to talk about the...
  47. C

    What is the Role of Damping Coefficient and Ratio in Vibration Theory?

    in vibration theory we talk about the following 1)damping coefficient 2)critical damping coefficient What is the intuitive meaning of the above two 3)damping ratio why we talk about the ratio of damping coefficient and critical damping coefficient? Vibration theory says that...
  48. C

    Forced Vibration Theory: Deriving Solutions for Displacement

    in deriving the solution for displacement in forced vibration theory is derived for complimentary solution and particular solution. Can anyone throw some light on the above solution. Why there are two solutions?
  49. I

    Could Fusion Cavitation be a Possible Factor in the Sun's Reactions?

    If we made a custom levitating coil like this: http://www.geocities.com/Area51/Shire/3075/globe.html so that we could suspend a small Iron ball in the levitation coil. Next If we added two small but powerful electromagnets to each opposite equatorial side of the Iron ball so we could play...
  50. C

    Analyzing Vibration of Bicycle Frame as a Spring Mass System

    I have a bicycle frame. I want to analyze this frame as a spring mass system. What details i should know. I should know the frame's stiffness. ok let us say it as x. Then the centre of gravity of the frame. Let us say it is also known. But now the frame can be pulled or pushed and then...
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