Questions tagged [vibrations]
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433
questions
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
votes
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 ...
0
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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
votes
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 ...
0
votes
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^{-...
1
vote
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
votes
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
votes
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
votes
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
vote
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
votes
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
votes
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
votes
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 cmā1) is a 3rd overtone (n=4)
The ...
0
votes
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{...
0
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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...?
0
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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
votes
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
votes
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 ...
0
votes
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
votes
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
votes
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
votes
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
vote
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
votes
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
votes
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
votes
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
votes
2answers
88 views
Difference between sound and high temperature [duplicate]
Though vibration is a common concept in sound and āhigh temperatureā, the essential difference between the two is mentioned to be the way the vibration takes place. The former has vibrations that ...
1
vote
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
votes
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
votes
1answer
53 views
Damped forced Oscillation with variable external frequency
Consider that we have the following forced vibration with an input frequency $Ļ(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
vote
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
votes
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
votes
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
votes
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
votes
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
votes
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 ...
