What is Vibrations: Definition and 235 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. zoki85

    Is the DE y''+ (1/x)y' + (1-1/x^2)y=0 solvable with explicit methods?

    y''+ \frac{1}{x}\cdot y' + (1-\frac{1}{x^2})\cdot y=0 Looks simple but it's a trouble.Probably unsolvable (explicitely). Recommendation?
  2. J

    Is it possible to use spectroscopy to see vibrations in a material?

    As I was walking to work yesterday, I thought about how each step I took on the concrete sidewalk spread phonons out in all directions. (Let me know if I'm misusing the term phonons.) Which brought me to the question in the title.
  3. S

    Help me visualize electronic vibrations

    Let's consider the simple functional group C=O (carbon double bonded to oxygen). There is only one type of vibration for this group and that's the stretching mode, where C<=>O oscillates back and forth. What exactly is happening during the stretching? Are electrons, and therefore electron...
  4. P

    Sound as longitudinal vibrations of air

    Sound is just Longitudinal vibrations of air that are detected from objects like the ear. Hence it originates from a vibrator. For humans this vibrator is in the neck in the form of a vocal cord. So sound from humans really comes from the neck and the vibrations of air ascend up the neck and...
  5. M

    Question about a research area (Vibrations)

    I am studying undergrad engineering I am looking for a good research area to apply for summer work next year and I was wondering if I apply to my university's mechanical vibrations lab would provide an interesting experience over other areas in mechanical engineering. I am wondering if this area...
  6. Cyrus

    Why I Love My Vibrations Professor

    I love my vibrations professor, he is simply the best. He always makes jokes in class. In one lecture he showed us a website to buy vibrations mounts from, he said "this website is like american express, don't leave home without it" Then when he was doing something in MATLAB he said, 'you know...
  7. P

    Solving Vibrations: Applying Energy Conservation to Find Natural Frequency

    Just started vibrations and having trouble applying energy conservation as a means of finding the natural frequency. So I know wn=root(k/m) and I know that Tmax=Vmax the problem is: In the complete assembly, the top of the float is connected to one end of a uniform bar (mass m and length...
  8. M

    Spider's Web Vibrations: Mass, Freq., & Spring Const.

    A small fly of mass 0.13 g is caught in a spider's web. The web vibrates predominately with a frequency of 1.0 Hz. (a) What is the value of the effective spring constant k for the web? (b) At what frequency would you expect the web to vibrate if an insect of mass 0.54 g were trapped? I...
  9. Cyrus

    Vibrations: Hell of a Class, My Teacher is Awesome!

    Man, that class is really insanely hard. Excuse me, while I go cry. :cry: :cry: My teacher has office hours the day before its due from 3-6. Basically, the ONLY way you can solve the homework, is by getting help from him, because its that hard. He gave us a problem and everyone got...
  10. B

    Equations of Motion for Transverse Vibrations in a Tensioned String System

    I'm stuck on question in where I need to set up a system of equations, can someone please help me with it? There are various things in this question which I just cannot figure out so any assistance would be great. Q. A light string stretched to tension T has its ends fixed at a distance 9L...
  11. E

    I need practice problems-Waves and Vibrations

    I need practice problems for Waves and vibrations course. Right now we are doing superposed vibtrations and I don't understand it. The book we have for the class is A.P. French and it has like maybe 10 problems in it and NO worked out solutions. I have REA's Physics problem solver but it doesn't...
  12. E

    Two Superposed Vibrations of Equal Frequency

    The Problem A particle is simultaneously subjected to three simple harmonic motions, all of the same frequency and in the x direction. If the amplitudes are 0.25, .20, and 0.15 mm, respectively, and the phase difference between the first and second is 45, and between the second and...
  13. C

    How Much Mass to Hang for Different Standing Wave Loops?

    One end of a horizontal string is attached to a small-amplitude mechanical 57 Hz vibrator. The string's mass per unit length is 4.4 10-4 kg/m. The string passes over a pulley, a distance L = 1.50 m away, and weights are hung from this end Assume the string at the vibrator is a node, which is...
  14. C

    How Do You Calculate Velocity at Equilibrium in Simple Harmonic Motion?

    A 0.55 kg mass at the end of a spring vibrates 2.0 times per second with an amplitude of 0.16 m. (a) Determine the velocity when it passes the equilibrium point. I have no idea how to figure this out i mean to figure out velocity ...we use this equstion vmax= 2pi*Amplitude* Frequency I...
  15. B

    Calculating Density of Immersed Weight using Vibrations and Fluid Statics

    Vibrations and Fluid Statics One end of a horizonatal wire is fixed, while the other passes over a smooth pulley and has a heavy weight attached to it. The frequency of the fundamental note emitted when the wire is plucked is 392 Hz. When the weight is completely immersed in water, the new...
  16. J

    Discovering the Force Constant of a Rubber Band: Methods and Formulas

    Describe two different ways to determine the force constant of a rubber band only a 100g mass, a stopwatch, and a meter stick. I don't really understand what its asking but I don't have many formulas to choose from so I don't really know where to begin. I have like f = 1/T y = A * cos...
  17. E

    Help me on my assingment on vibrations & wave

    help me on my urgent assingment on vibrations & wave 1.Two particles of masses m1 and m2 are attached to the ends of a rigid spring,the natural length of the spring is l and its tension is k.e.Initially, th particles are at rest with m1 at height h above m2 at t=0.mi is projected vertically...
  18. P

    Max Dist Compressed: .99m - Find Out How With Vibrations & Waves

    A 500-g block is released from rest and slides down a frictionless track that begins 2.00 m above the horizontal as shown in the figure. At the bottom of the track, where the surface is horizontal, the block strikes and sticks to a light spring with a constant of 20 N/m.find the maximum distance...
  19. G

    Science Consultant Advice: Vibrations from Spaceship Explosion

    Stupid question, not sure waht to say... In a science fiction movie, when a spaceship explodes, the vibrations form the sound nearly destroy a nearby spaceship. If you were the science consultant for the movie, what would your advice be for the producer? Anyhelp would be greatfully accepted!
  20. Greg Bernhardt

    Vibrations & Waves by Dr. Donald Luttermoser

    Author: Dr. Donald Luttermoser of East Tennessee State University
  21. J

    Are we really just vibrations, just energy

    ive read this before and I am checking up on it again now. i mean, does skin really exist. on a subatomic level, when you break it all down, isn't it just energy, just supposedly atoms, which are energy right? is the skin, blood, hair, the world, just a vibrational frequency of this...
  22. T

    Vibrations and the wave equation

    An infinite string vibrates according to the homogenenous wave equation u_{tt}-u_{xx} = 0 with initial data given by u(x, 0) =f(x) and u_{t}(x, 0) = g(x) for -infinity<x<infinity where both f and g are smooth functions that are positive on the intervals -4<x<-3 and 2<x<3 and both zero...
  23. E

    Exploring the Possibility of Sound Beyond 20kHz: Vibrations & Frequencies

    I'm currently studying vibrations and frequencies. I know that humans can hear from a range of 20Hz-20kHz. I was wondering if sound energy could reach a frequency where it was no longer really sound. Is this possible?
  24. quasar987

    Studying What other books cover waves and vibrations?

    I've run a search through amazon and I found that basically there are only 2 books about waves and vibrations: 1. 'Vibration and waves in physics' by Main, which looks good judging from the table of content 2. 'Vibrations and Waves' by French, which is the book I used for my W&V class but...
  25. H

    Forced vibrations w/ damping problem

    A spring is stretched 6 inches by a mass that weighs 8 lb. The mass is attached to a dashpot mechanism that has a damping constant of 0.25 lb-sec/ft and is acted on by an external force of 4cos(2t) lb. a) Determine the steady-state response of this system b) If the given mass is replaced by...
  26. S

    Answer: SHM: 45g Mass, .35m Amp - Speed Half Max Velocity

    How far from equilibrium will a 45 g mass with amp. of .35 m for a spring (k = 21 N/m) undergoing simple harmonic motion have a speed that is half its maximum velocity? a. .3 m b. .45 m c. .7 m d. .92 m e. 3.5 m Choice B is wrong. Use v = v_max*sqrt[1 - (x^2/A^2 m)] Do I use...
  27. I

    String Vibrations: Why Do Strings Move?

    Why do strings vibrate??
  28. S

    Motion of a particle performing damped vibrations

    Hi I have two questions to ask and hopefully someone could help as I am getting little help from my college and work collegues 1) The work done by an air compressor is given by W = K [ (p1/p2)^(n-1/n) + (p1/p2)^(n-1/n)-2] where p1,p2,n and K are all constants. QUESTION - show that...
  29. P

    Frequency of Vibrations & Waves in Guitar String

    A guitar string is 90 cm long and has a mass of 3.6 g. From the bridge to the support post (= L) is 60 cm, and the string is under a tension of 520 N. What is the frequency of the fundamental and the first and second overtone? :eek:
  30. P

    Solve Mass m: Frequency 0.88 & 0.60 Hz

    Need help please...I am having trouble with this question... :confused: A mass m at the end of a spring vibrates with a frequency of 0.88 Hz. When an additional 600 g mass is added to m, the frequency is 0.60 Hz. What is the value of m?
  31. R

    Designing Vibration Absorber: Questions Answered

    I'm trying to design a vibration absorber that will reduce the vibration of a machine by about 60%. I found the equations of motion of the machine without the absorber to be.. m1+x2"+ k1*x1+k2(x1-x2)+C2(x1'-x2')=Fo*sin(wt) and the absorber alone to be.. m1+x2"+k2(x1-x2)+C2(x2'-x1')=0 How...
  32. pelastration

    The Vibrations of Parapsychology

    Does ESP, telekinesis, pre-sight, ... exist? I understand that ESP is rejected by probably 90% of the posters here just because they don't accept is from a pure materialistic point of view. All depends however what is matter? Today physics confirms and most of use understand that matter...
  33. D

    Understanding SHM: Velocity of a Mass on a Spring at Max Displacement

    I am curious to know that if a mass on a spring undergoes SHM. when the mass is at its MAX displacement from equilibrium, its instantaneous velocity is what? is it zero! can someone explain? Dx :wink:
  34. V

    Understanding the Causes of Vibrations in Systems

    I would like to think that: vibrations do not come from thermal energy. A spring with two masses at each end of that spring do not vibrate due to thermal energy of the air around. That system vibrate because :when the spring is stretched, it creat a force pulling the two masses toward each...
  35. Bubonic Plague

    Uncovering the Mystery of Particle Vibrations

    Why do the particles of substances vibrate? Just where does that constant energy come from?
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