Questions tagged [vibrations]

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3
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1answer
92 views

Electronic-vibrational-rotational Transition

I'm trying to simulate the fluorescent spectrum for the first time and run into several problems. The dipole matrix element for a transition between 2 different electronic states is as follow: $$\...
0
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1answer
22 views

Why does bond vibration frequency depend on bond strength and atomic masses?

Why does a bond vibration frequency depend on the strength of the bond (does it relate to electrons shared in any way)? And why does it depend on the atomic masses of the atoms in the bond? I don't ...
0
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1answer
21 views

What are the phase speeds of $A_0$ and $S_0$ Lamb waves at very low frequencies?

Lamb waves are elastic wave modes in plates. In general, they are mathematically complex to deal with, and numerical solutions are typically used to find dispersion curves for each mode, as shown in ...
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0answers
25 views

Quantum confinement effect of phonons

I wonder what length scale is necessary to observe quantum confinement effects of phonons. I am supposing the situation of quantum wells (two dimensional). In case of electrons, by knowing Bohr radius,...
0
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1answer
29 views

Effect of acoustic wave striking an object

I am trying to understand the effect an acoustic wave has on an object. I have two speakers, one on top of another, and both emitting a Sine wave of 64Hz generated in MATLAB sampled at 44100. I place ...
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0answers
15 views

Energy of a damped oscillator how angular frequency affect

The total energy of a damped oscillator can be written as $\qquad<E>=E_0 e^{-2bt}$ but $\qquad<E> \text{also write as }\qquad <E>=\frac{1}{2}m\frac{v_0^2}{\omega^2}\omega_0^2e^{-...
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1answer
27 views

Lissajous Figure in SHM [closed]

Question In an experiment to obtain Lissajous figures, one tuning fork is of 256Hz and a circular figure occur after every five seconds. What deductions may be made about the frequency of the other ...
0
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1answer
63 views

String Theory Query

I listened to a lecture by Sean Carroll who gave a representation of "Strings" (as in string theory) by comparing them to a violin string. He said "A violin string can vibrate in lots of different ...
0
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1answer
28 views

Understanding a resonance experiment

This article states that If an object is being forced to vibrate at its natural frequency, resonance will occur I can understand how this definition applies to a playground swing: if person A ...
0
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1answer
53 views

Moment of Inertia using centre of mass knowing distance and weight of rod [closed]

I know the mass, I know the center of gravity position. Can i use this to work out the moment of inertia of a rod. So my ruler is 30 cm long and I know its mass to be 11.8g I have some blu tac which ...
1
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1answer
62 views

Diagram for the standing wave in a singing wine glass

Can anyone help me find a proper illustration of a standing wave that comes as a result of the superposition of the travelling waves in a wine glass? I am looking for something like (from this video ...
24
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7answers
5k views

If sound passes through material, vibration is produced. So are electromagnetic waves produced too?

Sound means vibration of molecules and vibration produces electromagnetic waves. So, this means that sound produces electromagnetic waves directly. Is this possible?
4
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1answer
47 views

Normal modes of vibration of a plate vs a membrane

I have been studying Chladni patterns but recently I have stumbled on some conceptual questions that I seem to not have an answer. At first I thought that the theory would be the same of a vibrating ...
0
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2answers
33 views

How to picture vibrational overtones of water?

Im trying to understand the colour of water. The absorption occurs because of some of the vibrational overtones of water. The absorption band at 698 nm (14300 cm−1) is a 3rd overtone (n=4) The ...
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0answers
7 views

Process to combine transfer functions/modal stresses with vibration test data

Generally the calculation process for the fatigue of components involve extracting the "modal participation factor" time histories from a "multi body dynamic" calculation and then this is combined ...
0
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0answers
51 views

What are degrees of freedom in this context?

For translational motion, $$H_\text{trans} = \frac{p_x^2}{2m} + \frac{p_y^2}{2m} + \frac{p_z^2}{2m}$$ For rotational motion, $$H_\text{rot} = \frac{1}{2} \frac{L_x^2}{I_x} + \frac{1}{2} \frac{...
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3answers
163 views

How can photons have frequency without vibration? [duplicate]

If photons have frequency then they must vibrate. So i was wondering, what kind of vibration do photons have? But according to physicists, photons do not vibrate. Can someone explain me, how is that ...
2
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1answer
43 views

How does the tuned mass damper on Taipei 101 work?

I'm interested in how the tuned mass damper on the top floors of Taipei 101 works, particularly how do engineers ensure that it dampens oscillation rather than making it worse. The damper can be ...
0
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1answer
49 views

Noise generated by ball impacting a rigid obstacle [closed]

How can I estimate the noise of an elastic non-deformable ball that hits an elastic plate that is simply supported?
0
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0answers
37 views

Determination of a phase shift function using wave equation

I have a question about solving for a phase-shift function. Suppose the function $$y(x,t) = A\cos(\omega t+\phi(x))$$ obeys/satisfies the wave equation $$\frac{\partial^{2}y}{\partial t^{2}} = c^{2}\...
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0answers
49 views

When using $\Delta \omega/\omega _{0}$ as a measure of how sharp a resonance is, why divide by $\omega_0$?

In A.P. French's Vibrations and Waves, page $111$, the author said the following about the sharpness of a given resonance, We can say that the resonance is narrow if the width is only a small ...
0
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1answer
33 views

Clothing fibres which would prevent the (vibration / resonance) effect live music has on the body

My 12 yr old cannot bear live music concerts. The bass, i think, hurts her entire body. She tells me she cant breathe, & the pain is a stab sensation in her chest & abdomen. Shes a very lean &...
0
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1answer
179 views

Eigenfrequencies of an elastic bar with viscous damping

I want to know the mode shapes and associated eigenfrequencies and damping ratios of a bar that vibrates in a longitudinal direction and has linear elastic as well as viscous material properties. ...
0
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1answer
57 views

Physics behind hissing sound when opening something that is vacuum sealed?

I am aware that it is the differences in pressure, and gases rushing into the container that makes the sound occur. But, what exactly is responsible for making the audible hiss sound when this ...
0
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1answer
64 views

Why things in motion make noise?

In most of the cases on earth,the things in motion definitely make noise but things at rest do not.For example:-boiling water,a body falling down,a man walking on road,flowing water etc. But the ...
2
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1answer
116 views

Has any scientist actually seen a $H_2O$ molecule vibrate?

Has any scientist experimentally confirmed that H2O molecules vibrate when heat energy is provided to them? Maybe by passing X-Rays through them or by some special camera...?
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0answers
6 views

Symmetrical design of a tuning fork [duplicate]

I was reading Ch. 10 of Kleppner and Kolenkow and I came across an explanation which said "The energy loss in a tuning fork is primarily due to heating of the metal. Air friction and energy loss to ...
-1
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1answer
40 views

How to understand motion of waves through functions of two variables - time and distance? [closed]

$$ s(x,t)= A \sin(\frac{2\pi}{T}t-\frac{2\pi}{\lambda}x) $$ Basically I would love to get some plausible and thorough explanation of plotting these two independent variables in order to satisfy the ...
4
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1answer
45 views

When a skyscraper sways in the wind, in which direction is the motion?

Skyscrapers sway in the wind (Source here). Which direction, relative to the wind, do they sway, ignoring effects of other buildings nearby? I can imagine wind from the North blowing a skyscraper's ...
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0answers
25 views

Vibrations in a cup of water

I realised that when a normal ceramic cup is placed on a table, and the table is knocked repeatedly, there seems to be a single focal point where there are circular waves on the inside of the cup ...
0
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0answers
18 views

Relation between output voltage and pressure field from a piezo

When applying a sinusoidal voltage with an amplitude $V_{pp}$ and a frequency $f$ across a piezoceramic transducer, the piezo vibrates and generates pressure fields. Is there a formula for the ...
3
votes
1answer
38 views

'Drummy' sound when striking with a hammer

In building there is a common test for masonsry structures that involves striking the structure with a hammer and listening to the resulting sound. If the sound is ringing the structure is fine but if ...
0
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1answer
23 views

The vibration of mechanical ondes

i want to ask about the relation highlighted in yellow in the picture the equation of motion of this system can be obtained using the Lagrange formalism, but my question is about this relation i have ...
2
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1answer
74 views

Do string instruments really create standing waves or not?

I have seen similar questions regarding this but containing answers that somewhat disagree with each other which makes it hard for me to understand this. My question is mainly about when plucking a ...
1
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0answers
18 views

Energy in a vibrating part of an engine

I have sensor data of the vibrations of the parts of an engine. I was wondering whether I could calculate how much energy a part contains in a given time window. Now the energy of a wave given by ...
0
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0answers
33 views

How does vibration transform after rotation of the vibrating object?

I can't find the math of that. Imagine a vibrating object, like a circular membrane, with vibration modes $\phi_{ij}(x,y)$. Let's express the initial vibration state like $u(x,y,t)=\sum_{ij}a_{ij}e^...
0
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1answer
59 views

Different energy levels in quantum mechanics

I have a doubt regarding energy levels. I saw that translational energy levels are quasi-continuous, rotational energy levels are discrete and vibrational energy levels are more discrete. I want to ...
6
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3answers
484 views

Vibration on the guitar when playing two strings

I know that when I am playing one string on the guitar, it creates a standing wave which causes the entire body vibrates in its frequency and therefore create sound waves. But, what about two strings? ...
0
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1answer
20 views

For vibrations in continuous beam, what is the unit of eigenvalue?

I have been solving a fourth order euler bernoulli differential equation to solve for vibrations of a continuous cantilever beam. When I verified for them using Comsol eigenvalue solver, it gives me ...
4
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2answers
88 views

Difference between sound and high temperature [duplicate]

Though vibration is a common concept in sound and “high temperature”, the essential difference between the two is mentioned to be the way the vibration takes place. The former has vibrations that ...
1
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2answers
2k views

Difference between Oscillatory motion and vibratory motion

What is the difference between oscillatory motion and vibratory motion. I have read in my book that "If the amplitude of oscillatory motion is extremely small,the motion is called vibratory motion". ...
0
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1answer
197 views

Frequency of longitudinal waves on a string

I recently heard the composer Ellen Fullman on her Long String Instrument, which consists of steel wires of approx. 20 m length played by rubbing/stroking the string longitudinally. Changing the ...
0
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1answer
53 views

Damped forced Oscillation with variable external frequency

Consider that we have the following forced vibration with an input frequency $ω(t)$ variable in time. $$m\ddot{x}+c\dot{x}+kx = F_0 \sin{(\omega(t) t)}$$ Assuming that the solution must be a ...
1
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0answers
34 views

Spring oscillation model

When a spring - in real world - is extended $Xo$ from its natural position, it oscillates and eventually decreasing it's amplitude with time, comes to a stop. Is this a damped system or no? If yes how ...
0
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0answers
37 views

Coupled Harmonic Oscillator (Forced Vibration)

I derived two equations for a 2DOF harmonic oscillator system, declared state variable equations, and placed them into matrix form: $Ax' + Bx = C$. I have a Matlab script to determine the constants ($...
8
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3answers
450 views

Why choosing for prime numbers eliminates vibration?

I have read that the spokes of a car wheel are usually five because, besides other substantial reasons, five being a prime number helps to reduce vibrations. The same also happens with the numbers of ...
0
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1answer
30 views

Producing harmonics of standing wave on a string at non-coprime divisions

I am currently researching the properties of producing harmonics on a vibrating string fixed at its ends (e.g. violin). Lightly touching a node at division of the string a/b will sound harmonic b iff ...
0
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0answers
40 views

At what rate is tension released from a plucked string (eg. guitar string)?

Tension in a plucked string (such as a guitar) dictates many of the important changes that occur in the sound of the string over time. eg. It causes a pitch bend, a change in inharmonicity, and ...
0
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2answers
237 views

A hypothesis based on the principle of conservation of momentum

When a ball hits a wall (ground), some quantity of its momentum must be transferred to the wall at rest. If else the ball would bounce back with the exact same speed as it did when it collided with ...
0
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1answer
139 views

Vibrations in Stones and Crystals [closed]

I have read studies done that indicate certain sounds can either disrupt or reinforce the molecular structure (I think this is the terminology used) of living organisms. This is based on the idea that ...

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