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.

View More On Wikipedia.org
  1. I

    I Nuclear Vibrations: Krane pg 141 | 0^+ State

    In a passage of our book (Krane page 141) they add two quadrupole phonons to a ##0^+## state. So as I understand it these phonon can be written in the form ##Y_{\lambda \mu}## with ##\lambda=2##. It makes sense that this corresponds to two units of angular momenta. Then they talk about the...
  2. G

    How does increasing the tension of a string affect various properties?

    This isn't really a homework question, just a question i got wrong on test and want to understand: If the tension of a string increases how would the following be affected (Increase, decrease, stay the same, not enough info)? 1. The fundamental frequency of vibrations on a string? 2. The...
  3. RicardoMP

    Normal Modes and Normal Frequencies

    Homework Statement I have to determine the frequencies of the normal modes of oscillation for the system I've uploaded.Homework Equations [/B] I determined the following differential equations for the coupled system: \ddot{x_A}+2(\omega_0^2+\tilde{\omega_0}^2)x_A-\omega_0^2x_B = 0...
  4. L

    A What Makes Vibrations So Common in Nature?

    Vibrations are everywhere and the question is if there is some fundamental reason for this. Per example, symmetries and the least action principle are behind the conservation laws. What is the reason that vibrations are so common?
  5. ltkach2015

    Why Time Response Characteristics Derived from Zero State Equation

    QUESTION: 1) Why are Time Response Characteristic's Expressions derived from only from Zero State Equations? NOTE: Nise Control Systems Engineering 6ed uses step inputs to derive Time Response Characteristics for 1st and 2nd order ordinary differential equations...
  6. Spiralone

    Create educational tools to explain mechanisms & vibrations

    Hello, I have to hold a short course on applied mechanics and mechanical vibrations and I would like to develop a tool similar to the one shown in the linked webinar below (min 27.43): https://www.youtube.com/watch?v=0TH5SLghYPY&t=27m45s What do you think would be the best software to develop...
  7. Sace Ver

    How Many Vibrations Does a 880Hz Violin String Make Over 332m?

    Homework Statement A violin string is vibrating at a frequency of 880Hz. How many vibrations does it make when the sound produced travels 332m through air at temperature of 0 degrees Celsius. Homework Equations Not sure. The Attempt at a Solution I'm not quite sure how to solve this equation.
  8. Runei

    Axial/Longitudinal Vibrations in beams

    Hi there, I'm studying for an exam in mechanical vibrations, and I'm at the moment looking at longitudinal waves in continuous beams - and I've run into some problems. The whole idea is to explain the solutions of the system in terms of eigenvalues and eigenfunctions, which is not that big of...
  9. H

    Problem with molecular vibrations

    In IR spectroscopy, bonds vibrate and therefore there are moving charges and usually a changing dipole. If accelerating charges cause EM waves to be given off due to the changing electric field then shouldn't the vibrating bond be constantly emitting photons and therefore losing energy in a...
  10. B

    Vibrations of a Violin (Physics)?

    so my group was given this topic to discuss in physics. What are some sub topics that i can talk about? i don't know where to start my research example: 1) how a violin makes sounds? - - 2) _____
  11. U

    Good source homework problems for beam spring structures?

    Hello there, In this semester I'm studying the vibrations course. In this course we get questions like calculating the total stiffness, set up differential equations and so on. The book that we use (Theory of Vibrations) has not been very useful, our exams give beam spring structures related...
  12. V

    Why Does Sound Get Produced? Exploring Vibrations & More

    Why is sound produced? Say, for example, when a stone hits a tin box a sound is produced. Why is this sound produced? Even if the sound is produced in the ear, we generally say that the vibrations of the ear drum produces the sound, why is it produced. Why does vibrations produce sound. Even a...
  13. Observeraren

    Vibrations in a glass with water.

    So I just poured water in a glass to clench my thirst. Hit the 2/3 empty glass with a pen and a high frequency started resonating for a brief moment, which I percepted as sound. When I tilted the glass the tilt resulted in change of frequency. When the glass was empty there was no change in...
  14. E

    Driven vibrations, seismometer

    Hello guys, this question showed up in my test last week as a challenge question, but the problem is, I'm the first year at college and have not yet learned to solve differential equations. Of course I did not manage to do it but I´m pretty eager to learn. Thanks in advance
  15. R

    Amplitude and Vibrations in Springs

    Homework Statement The amplitude of vibration of a mass on a horizontal spring experiencing SHM is = 0.13m. The mass is 85g and the force constant is 55N/m. a) What is the maximum elastic potential energy of the system. b) Find the speed of the mass when it's position is x = 7.4cm from the...
  16. Erikono

    Newton's Method for Equations of Motion (Vibrations) help?

    Homework Statement Determine the equations of motions in terms of x and gamma. Assume small angles and that the wheel rolls without slip. The mass of the thin homogeneous large disk of radius 2R is 2m. The mass of the thin homogeneous inner disk of radius R is m. The rod of length 2R is...
  17. A

    Uniformity of thermal vibrations

    Hello, I have a question on the nature of vibrations due to thermal energy. Earlier today I read this article which talked about cooling a glass string to near absolute zero using feedback from a high precision sensor. http://phys.org/news/2015-08-smallest-vibration.html what I understood from...
  18. J

    Classical Book like Barret/Bekefi's Electromagnetic Vibrations?

    The book is expensive, so I want a book like Bekefi's and Barrett's Electromagnetic Vibrations,Waves,Radiation. Preferably at a higher level than this book. Thank you!
  19. B

    Creating Vibrations using a Small Device

    I'm creating something as a side-project, but I've encountered a problem in a field I'm not well-versed in. There is a material I am looking to excite with a resonance frequency of 50 Hz. I need the smallest possible device to create the largest amount of vibration, I've looked into some small...
  20. B

    What's the Best Device for Simulating Car Vibrations?

    Hi everyone! It's my first time working with vibrations (and on this site) and I'd like to know what the best device is for simulating a car engine's vibrations is. Basically I want to generate a random range of frequencies. I would like to keep it as small and for it to use as little power as...
  21. E

    Medical Why do we enjoy listening to music?

    I've been researching this subject for a little while. I'd like to hear your ideas, because the topic is widely discussed. So here is some part of my research which makes my opinion quite clear: "Sometimes we say , that one is moved by music. Of course, it does not mean for him/her to be...
  22. bananabandana

    Longitudinal Wave Equation from Transverse One

    Homework Statement Please see attached. Part ii) Homework EquationsThe Attempt at a Solution So I try to conserve volume as it suggests in the hint. I take the initial volume of the region to be given by: $$ h \times \delta x \times l = (\delta x + \eta) (h+\Psi) l $$ Where l is just some...
  23. N

    Spring mass pulley system frequency equation

    Homework Statement A spring is attached to the ceiling, a pulley is attached to the other end of the spring, a string is suspended over the pulley, and a mass attached to the free end of this string. The system oscillates vertically. Can someone PLEASE help me derive this equation for natural...
  24. S

    Equation of Motion for pendulum suspended from a spring

    Homework Statement Derive Newton's and Lagrange's equation of motion for the system. Discuss differences and show how Newton's equations can be reduced to lagrange's equations. Assume arbitrarily large θ. The system is a pendulum consisting of a massless rod of length L with a mass m...
  25. T

    Mechanical Vibrations Coursework: Frequency of Block Rolling in Water

    Homework Statement I am currently taking mechanical vibration course and am given coursework. A wooden block (20X200mm) floats half submerged in water. Determine the frequency of small oscillations of the block rolling from side to side. In this motion, the centre of mass remains in the plane...
  26. Graeme M

    Exploring the Nature of Sound and Vibrations

    I know there is a previous post here about this, but it didn't seem to cover the angle I am getting at... I understand sound to be vibrations that travel through a medium such as air or water. However, what actually generates these vibrations? For example, hitting a piece of steel with a rod...
  27. G

    Problems/solutions manual/pdf/website waves and vibrations

    Hi, my teacher is pretty bad at teaching, my book offers problems with no solutions and poor examples, and there is no solutions for the problems on the internets. Does anyone know a manual/pdf/website where I can find problems and solutions for waves and oscillations? I have read the book and...
  28. M

    How do vibrations in a solution affect other particles?

    Hi, I was wondering if someone can explain to me the following. If I have a vibrating molecule in a solution, what effect would this vibration have on other particles in my solution which are different. Can the vibration be the same for them if they are not excited (do not vibrate due to...
  29. G

    Structural Vibrations Analysis & Simulation

    Recently I created a structural vibrations simulation and would like to hear some feedback or suggestions.
  30. L

    Finding the Maximum Displacement and Time of a Piston in a Spring-Damper System

    I know this question has already been asked, but the given answer di not help me. Hopefully someone can post their full solution? A piston of mass 4.53(kg) is traveling in a tube with a velocity of 15.24(m/s). It engages a spring of stiffness 350 (N/cm) and a damper with a coefficient of 1.75...
  31. D

    Modeling a quad rotor vibrations

    Homework Statement I have a system of five coupled ODEs. I believe I should be able to reduce it down to four coupled ODEs, but I am not sure how. This system is modeling a quad X rotor where the arms are viewed as end loaded cantilever beams with motors attached. Homework EquationsThe...
  32. T

    Vibrations - Rayleigh-Ritz Method Admissible Functions

    Hi everyone, I'm having a bit of difficulty choosing an admissible function for a fixed-fixed nonuniform bar. I chose the function φ(x) = 1 - cos(2πx/L). But when solving for the the stiffness and mass coefficients: kij = ∫EA(x)φiφjdx mij = ∫ρ(x)φiφjdx, I am not sure where I should have...
  33. A

    Vibrations of a circular membrane with free ends

    Hello, As of this moment I am trying to get in the process of writing an Extended Essay on Chladni Plates, more specifically on a circular vibrating membrane with free ends. To begin with I thought the concept could be simplified to such an extent where I could take a cross-section of the plate...
  34. S

    Vibration/Centrifugal Force Question

    Hello I am making a vibration project which requires me to mount eccentric weights on both sides of an electric motor. I must submit the "generated force(in Kg)" by this motor.The RPM of motor = 1000 Total weight on both sides of the motor = 16.8Kg (8.4Kg on both sides) The radius(distance from...
  35. D

    M.S. Mechanical Engineering in Mechanics vs Robotics/Controls

    Hello fellow PF members, I'm currently in my senior year in Mechanical Engineering at Oregon State University. I'm considering going on to get my Master's Degree to gain more knowledge (since I'm fascinating by them). I really like Math and have a Math Minor already. I am looking to go into a...
  36. Subhadeep Dey

    Applications of Damped Oscillation (in Vibrations): Researching for a Paper

    I've been researching on Damped Oscillation (in vibrations) for a few days for a research paper, however I couldn't find any applications. I would be very thankful if anyone can tell me about its applications.
  37. anubodh

    Space-Time Vibs: Moving Objs Effects & Cycle

    Does both space & time vibrate when objects move or when they vibrate when objects accelerate? So, what happens of these vibrations? How are they converted back into matter to maintain a cycle?Do these vibrations affect the motion of other moving objects (although negligible)?
  38. M

    How to Solve a Mixed 2 DOF Vibration Problem with Incorrect Free Body Diagram?

    I am struggling with the following question, it is a mixed (lever and linear) 2DOF vibration problem, something I never came across before. I am afraid I am missing something on the FBD, thus the differential equations of motions are wrong. Homework Statement Homework Equations...
  39. C

    Atomic Vibrations & Time Dilation: The Reality Behind Our Perception

    We measure time based off of atomic vibrations, so time dilation from gravity and velocity are nothing more than pressure applied to the atoms, slowing their vibrations. This isn't an accurate measure of what we consider time, but more of a measure of the reaction of atomic vibrations under...
  40. S

    Modal Analysis for Safe Region in Automotive Vibrations

    can i locate region in an automotive, which is safe from vibrations, by modal analysis? can i conclude that blue region in mode shape a safe region?
  41. A

    How do compound objects maintain rigidity despite atomic vibrations?

    Hello, as we all know, in compound solids atoms are always vibrating with some degree, depending on the temperature or the average kinetic energy they posses. My question is how do compound objects maintain their rigidity in those conditions, or to say it better how do atoms stay in fixed...
  42. electricspit

    Vibrations of Triatomic Molecules, Landau-Lifshitz

    Homework Statement https://ia701205.us.archive.org/11/items/Mechanics_541/LandauLifshitz-Mechanics.pdf Page 72 of the book itself, but Page 81 of the PDF. Problem 1. Homework Equations See Section 24 of the book. The Attempt at a Solution So far I have completed and...
  43. J

    How Does Trigonometric Identity Simplify Forced Vibration Equations?

    I am trying to work though an example on this topic in my book and have reached a point that I am not sure about. I was wondering if anyone could help me clear this up. The equation of motion for a spring-mass system with no damping and a periodic external force is mu'' + ku = Fcos\omega t...
  44. V

    Will truss linkages diminish vibrations?

    Is it possible to have a body supported by truss linkages and isolate them from any stresses and impulses? Say, we are supporting a platform on the top of a set of rigid, pin jointed and cross-linked members. If small impulses act on the bottom on the linkages(upwards), is there any...
  45. vanceEE

    Solved: Forced Vibrations Homework: Using Arctan

    Homework Statement $$ M \frac{d^2x}{dt^2} + c\frac{dx}{dt} + kx = F_{0}cos \omega t $$The Attempt at a Solution $$x(t) = asin\omega t + bcos \omega t $$ $$ a = \frac{\omega c F_{0}}{(k-\omega^2M)^2 + \omega^2c^2} $$ $$ b = \frac{(k-\omega^2M)F_{0}}{(k-\omega^2M)^2 + \omega^2c^2} $$ $$ x_{0}(t)...
  46. A

    Proton Vibrations: The Behavior of Protons When Not Bound to Nucleus

    Hi all, a) Do a proton still vibrate if it isn't bound to its nucleus? I mean, if it is "alone" (no neutron, no electron). Do anybody know if they have done experiments on it? I would like to know if it has been observed/measured in some way. b) An electron does not "like" to be still, it...
  47. L

    Simple Harmonic Motion vibrations

    Homework Statement Find the period of low-amplitude vertical vibrations of the system shown. The mass of the block is m. The pulley hangs from the ceiling on a spring with a force constant k. The block hangs from an ideal string...
  48. J

    Mechanical vibrations - waterfall plots

    hi! i'm beginner in the subject of vibrations. i'm trying to understand the waterfall plots. i have attached a waterfall plot. can someone please help me to understand it? waterfall plots are used when the operating speeds are varying (run up or coast down). in this plot, as the...
  49. K

    Why Are Detectors for Molecular Vibration Frequencies Less Common?

    We have common detectors for radio, microwaves, visible, ultraviolet, xray and gammy rays.. but how about the infrared frequencies from molecular vibrations. The frequencies of molecular vibrations range from less than 10^12 to approximately 10^14 Hz. These frequencies correspond to radiation...
  50. R

    Nonliear Vibrations- Incremental Harmonic Balance Method

    Homework Statement Consider the van del Pol equation [tex]\ddot{u}-ε(1-u^2)\dot{u}+u=0[\tex] Determine the limit cycle for ε=1 using the incremental harmonic balance method. Validate the result using numerical integration (e.g., Runge Kutta). Homework Equations It's incremental...
Back
Top