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Questions tagged [vibrations]

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Vibrations with Different Frequenc'es Beat

Hello here i have a problem which is following Say there are two waves which are $x_1=A_1cos(w_1t)\\x_2=cos(w_2t)$ In my book it is written that $x=x_1+x_2=2Acos\frac{(w_1-W-2)}{2}tcos\frac{(w_1+W-...
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1answer
413 views

Energy Conservation of waves at a boundary

Consider a wave traveling on a string with velocity $\upsilon$ and mass density $\rho$ having unit length so that the mass of the string is $\rho$. Considering the string to be a simple harmonic ...
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0answers
45 views

Is LIGO designed as a bandpass instrument?

This question intended for those that may have personally worked on LIGO and are knowledgeable about its detailed systems architecture. I understand that LIGO basically uses a Michelson-Morley type ...
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2answers
1k views

What actually is the wavevector in the context of phonons and lattice vibration?

When we deal with Electromagnetic waves the wavevector has the meaning that it encodes the information about the direction of propagation, together with the wavelength. In Quantum Mechanics, the ...
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2answers
138 views

What characteristics define a wave for a physicist?

What characteristics define a wave for a physicist? Any superposition of two arbitrary functions $f_1(x-vt)$ and $f_2(x+vt)$, satisfies the wave equation in one-dimension. Will it be called a wave if ...
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2answers
2k views

Frequency of Damped Vibrations [duplicate]

In the chapter sound, my book states that the Frequency of damped vibrations is less than the natural frequency but I could not understand this because in damped vibrations the amplitude decreases and ...
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1answer
89 views

How does QFT explain the difference in behavior of photons and regular matter?

In QFT, photons are vibrations in the electromagnetic field and matter is also vibrations in many fields. These vibrations result in things that behave in completely different ways. How does QFT ...
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1answer
366 views

String Vibrations

Interesting thing I noticed just now playing my ukulele. For those who don't know how a ukulele works, it has four strings: a high G followed by a lower C, E, and A. Holding down frets causes the ...
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0answers
87 views

Deriving Potential Energy Density for Longitudinally Vibrating String [duplicate]

I understand how to derive the density for a string vibrating transversely. However, for a longitudinal one, I had some doubts. Namely, suppose $ y(x,t) $ is the extension of some point (really, ...
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1answer
138 views

What is the difference between note, tone and mode?

What is the difference between note, tone and mode? In physics, wave mechanics and vibration specifically, do the terms note, tone and mode mean the same thing or do they refer to difference things?
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3answers
910 views

Normal modes of the 3-mass-spring system

This question might seems naive, but I'm not a physics student and got puzzled here. There are three masses placed on the plane and they form the 3 vertices of an equilateral triangle. Every two of ...
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1answer
12k views

If all matter is vibration, what does actually vibrate? [closed]

There is a theory, that all matter is energy in vibration in it's core. I have read a lot of articles and watched a lot of videos and documentaries about that topic and they all state, that there is ...
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3answers
1k views

Do soundwaves produce heat?

Sound dies down after a while. The energy emmited by the speakers must go somewhere. Where does it dissipate this energy? Is it in heat? Theoretically, if i play music in a room, would it get hotter ...
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2answers
3k views

How does a vibratory bowl feeder cause the parts to move up?

When I first learned about bowl feeders I thought that there was some sort of rotation that would cause it to go up, but apparently it is caused by vibrating the bowl. I do not understand how ...
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0answers
63 views

The lightest, stiffest, and largest panels available are made of what?

This document on audio exciters lays out some uncited requirements for the best sound from an excited panel: A stiffer panel will give better high frequency (treble) performance. A lighter panel will ...
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1answer
238 views

About energy equations of unidimensional transverse waves

Studying the unidimensional waves, at least 3 books, and a lot of address on the web used the following idea (at least i think that it happened): In order to describe the rate of change of potential ...
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3answers
26k views

What are the first, second etc modes of vibration?

What is the first, second etc mode? I cannot find online explanations. Is it the shape of vibration? Does a thing have more than one natural frequencies (first, second, etc) and it vibrates with ...
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1answer
108 views

What decides membrane mode shape 'direction'?

Consider the modes of a circular membrane which has perfectly isotropic mechanical properties. The fundamental mode 01, has a symmetric shape as does 02 etc. However, for example the mode 11 has a ...
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1answer
32 views

Acoustic decoupling of small mechanical resonator

I am trying to lock and optical cavity mounted on a small aluminium breadboard. I notice when locking that any sound, even quiet whispering seems to disturb the process, causing a 100hz fluctuation to ...
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1answer
272 views

What do resonant frequencies of the Helmholtz equation correspond to in the wave equation?

Time-harmonic electromagnetic and acoustic waves are governed by the Helmholtz equation $$\Delta u + k^2 u = 0,$$ in the frequency domain. This is an eigenvalue problem for the Laplacian and the ...
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1answer
677 views

How to calculate the damped frequencies of a linear system?

I am dealing with a vibration problem. The system is free to oscillate and its mass, stiffness and damping matrices are $$ M = \begin{bmatrix} 60 & 23.5 & 0\\ 23.5 & 15.996 & 0\\ 0 ...
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1answer
1k views

Difference between polarizability and dipole moment

I am reading about Raman spectroscopy in general. And I learned that Raman spectra reflect the changes in the polarizability of a molecule, while the IR spectra reflect the changes in the dipole ...
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1answer
1k views

How does tension in string change when object suspended from it is dipped in water?

A copper cylinder hangs from the bottom of a steel wire of negligible mass. The top of the wire is attached to the ceiling, and once struck the wire emits a sound with a fundamental frequency of 300Hz....
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1answer
2k views

Can a human sized object vibrate so fast it appears invisible to the human eye? [duplicate]

my brother and I are working on a story in which a being's atoms vibrate back and forth so rapidly that it appears invisible, like a plucked guitar string or a plane's propellor. Is that ...
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2answers
60 views

What causes some gas diffusion to be noisy, others to be quiet?

My question is about noise in gas diffusion, specifically when a can of pressurized gas is opened into the atmosphere. I want to know why this is noisy sometimes, but quiet other times. Does the gas ...
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1answer
60 views

Generation of waves [closed]

How does a wave generate from a physical phenomenon? i.e. how we can actually feel that a wave is generated through a physical process? For example I actually want to know when the spring bounces how ...
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2answers
1k views

Calculating Intensity/Strength of Vibration with 3DOF

I want to calculate the intensity/strength of vibration at a given location. I have measured the acceleration at this location, using an accelerometer. So my measures look for example like: ...
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1answer
58 views

Reducing coefficient of friction by vibrations?

Very simply put, if one places a block of some material on a level surface and pushes it horizontally, a certain coefficient of friction is measured. If one tightly couples an oscillator of some sort ...
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1answer
92 views

Vibrations of a string [closed]

A string with length $L$ is stretched between two fixed points. The string can't vibrate with which wavelength? Four options are given, namely $L$, $L/2$ , $2L$ and $4L$. I know that the ...
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0answers
69 views

What's the effect called when vibrations move through a cable under tension?

I'm not sure how to describe it, but there is a certain sound of vibrations through a tensioned cable, you might hear it as sound effects in a movie where cables are snapping, some have described it ...
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1answer
37 views

looking for a technique for conducting experiment [closed]

I have used a servomotor and a controlling circuit to produce oscillatory motion for an experiment that involves flapping of a tiny metal plate (~few mm) inside liquid. I could not be very successful ...
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1answer
42 views

Outbalancing vibrations

Consider a ship vibrating in the fundamental/principal/first symmetric mode shape (similar to that of a Bernoulli-Euler beam), induced by the main engine (similar to that of a vibration shaker). I ...
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2answers
47 views

Difference in Energy Transfer Between Impacts and Nudges [closed]

Say I have a table and I want to produce a vibration in the table. Would I be better off impacting the surface of the table (i.e. smacking the table) or nudging the surface (i.e. leaning on the ...
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1answer
861 views

How does string tension influence the harmonic spectrum?

Hey there fellow physicists & musicians! I have a question both physics and music related. How does the string tension affect the sound spectrum? More precisely, how do the respective ...
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2answers
3k views

Is Everything Vibrating?

It is often said that "everything is in a state of constant vibration". What led to this statement? And can I get any source of this statement that I can cite?
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0answers
56 views

What is Lamè mode?

I am trying to read some of the articles that says Lamè mode. But I can't find in google that describes Lamè mode. Can anyone quote good reference for this term?
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0answers
127 views

Is disturbance propagation velocity equal to wave velocity in a solid body?

How do the disturbance propagation velocity and wave propagation velocity relate to each other? To explain my question in details I will describe the following situation from the theory of acoustic ...
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2answers
842 views

How to derive wave speed/tension relation for the vibrating string?

I was studying vibrating strings and in my teacher's notes I found that, generically, if I change the tension on the string by $\Delta T$ then, the speed percentage change can be written as: $\frac{\...
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1answer
245 views

What is the exact mathematical definition of oscillation/vibration?

My question is basically is what criteria need to be fulfilled to decide wether a motion is osciliiation/vibration or not. I found two definitions, def1: "moving around an equilibrum", def2: "...
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3answers
3k views

Why don't metals damp vibrations?

Fluid damps vibrations due to viscous dissipation. Does anyone has any insight on a molecular, microscopic level about the reasons that vibration damping of metals is negligible?
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2answers
912 views

What's the origin of electrical resistance?

i know relation ohm : $$R=\rho\frac{L}{A} $$ i want to know about resistance from view point small particle like atom,dipole: when we have a resistor,with a special voltage it has loss power: whats ...
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2answers
86 views

What information am I losing out when I assume that the displacement in S.H.M. is small?

While making calculations for simple harmonic motion, we take the force as $F=F(x)$. Then we use Taylor's expansion and calculate as follows: $$\begin{align} F(x) &=F(0+x) \\ & = F(0)+xF'(0)+...
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0answers
360 views

What is the highest frequency for ripples on water

I want to transmit sound vibrations as ripples on water, as an experimental audio delay effect. Can I make ripples at audio frequencies, that will travel over about 10cm or more? How about other ...
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2answers
3k views

What's the difference between vibrational relaxation and internal conversion?

According to the following diagram, an excited state can dissipate via vibrational relaxation or internal conversion. Aren't they the same thing? (source: Barltrop and Coyle, Principles of ...
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0answers
103 views

Why are vibrations so common? [closed]

Why are vibrations so common? We all know, or pretend to know, that symmetries and the least action principle lead to conservation laws.Is there something more fundamental behind the fact that ...
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1answer
565 views

3D Standing wave [closed]

I need to derive an equation (like a vibrating string) of a 3D vibrating object having a mass ‘m’(object itself made of bunch of closely packed particles, in-between the particles there should be an ...
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1answer
104 views

How can frequency of waving in water change the direction an object on the surface goes?

In an Australian experiment the physicists studied effects of a simple object that causes waves in fluid. They found that if it vibrates slow, the objects on the surface move away from the source of ...
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1answer
158 views

Are ALL vibrations an exchange of kinetic and potential energy?

I'm taking a course on mechanical vibrational analysis and this is what I was told by my professor, but I'm curious if there are any counter-examples.
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1answer
244 views

Oscillation of non-uniform plank on parallel springs

A plank of length $l$ and mass $m$ is placed on two parallel springs, each with spring constant $k$ and equidistant from the plank's horizontal center of gravity. When the plank is displaced from it's ...
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0answers
2k views

Is it possible to generate deep infrasound with subwoofer and a pipe?

I would like to check if infrasound noise can make people feel weird (as in a "haunted" house). Some people claim that noises of such frequency may be the cause of "paranormal" sensation in humans. ...