Questions tagged [vibrations]

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2
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1answer
105 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
160 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. ...
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2answers
2k views

Do homonuclear diatomic molecules interact with infrared light?

A molecule will appear on IR spectra if its dipole moment changes during vibration. Due to symmetry, the dipole moment of homonuclear diatomic molecules ($\mathrm{H_2, N_2, O_2, F_2, \dots}$) is zero. ...
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1answer
144 views

Why hydrofluoric acid (HF) has two Raman bands?

Hydrofluoric acid (HF) is a diatomic molecule with only one vibrational coordinate. Therefore I would expect only one Raman band, however there are two. Why? (source)
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2answers
5k views

How does a flute produce its sound?

if an object for instance does not create successive compressions and rarefactions in air but only creates continuous compressions would we be able to hear these compressions as sound ? Yes , because ...
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2answers
244 views

Why doesn't steady flow of air create sound? [closed]

When one exhales air by twisting the lips appropriately, one does not create enough sound. But when the same amount of air with the same pressure is blown in a flute or whistle, a relatively audible ...
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2answers
723 views

Amplitude at successive wavefronts?

Consider a spherical waves emanating from a point source initially having the amplitude is $A$. As he wave travels, forming wavefronts, will the amplitude of each point in all the secondary wavelets ...
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2answers
256 views

Why do the tones differ when tapping on a different part of a coffee cup?

Let's say we have a coffee cup as shown below. The cup is, in contrast to what's shown on the image, empty (I had some trouble finding free good-quality top-view coffee cup images). When we tap on $\...
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2answers
635 views

What is torsional vibration?

Specifically, what is happening physically if a metal rod experiences torsional vibration? Googling torsional vibration brings up a load of research papers, well beyond the level I'm at. I can't seem ...
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2answers
412 views

Is this SISO (single input single output) or MIMO (multiple instead of single) system?

If I transform wave equation for vibrating string Mx′′+Cx′+Kx=b(t) in linear system using $x_1(t)=x(t)$ and $x_2(t)=x_1^{'}(t)$ vibrating string equation becomes $Md_tx_2(t)+Cx_2(t)+Kx_1(t)=b(t)$. ...
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2answers
2k views

Can you hear vibrations through your bones?

If we have a source, like a speaker, but with no sound and only the vibrations, and this vibrations were transported to a surface which you can put your elbows on it and then put your hands to your ...
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0answers
37 views

How can one prove mathematically using a thought experiment that a simple pendulum will vibrate forever in an ideal condition (no friction) [duplicate]

Let's say I have a simple vibrating pendulum, if there is no friction in the space, will it vibrate forever or will it stop? How can one prove this mathematically? I tried but failed, can somebody ...
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2answers
97 views

How much energy would it take to take down a 747 using vibrations? [closed]

Background Information: All materials have a resonant frequency, which is the frequency at which they are most easily excited (vibrated). That's how glass is shattered using high-pitched sounds. ...
4
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3answers
157 views

Would a bag of neutrons have temperature?

Neutrons interact with each other only via exchange interaction, while "every-day particles" and their temperatures are governed by electrostatic forces. What are the implications of this difference ...
3
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1answer
76 views

Traveling wave solutions for an irregular “waveguide”

I'm looking at solutions for the wave equation $$\frac{\partial^2 z}{\partial t^2}=c^2 \nabla^2z,$$ in a finite 2D domain. Say that I have periodic boundary conditions on the left and right edges ...
3
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3answers
386 views

How can $F_0\cos\omega t$ change to $F_0e^{i\omega t}$ in driven oscillator equation?

I have one thing that confuses me on deriving the solution for the Linear Forced Oscillator. Suppose we have the equation as $$ma + rv + kx = F_0 \cos \omega t$$ What confuses me is when the driving ...
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1answer
1k views

What is a clear definition of vibrons?

What is a clear definition of vibrons? Vibrons are localized Phonons and I need more information about them. It is somewhat vague to me. Can you give some references, please?
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0answers
314 views

How was the “vibrating string” studied?

The vibrating string is used to derive a lot of theory regarding strings, such as the theory about harmonics. However, since the string movement and specifically the phenomenon of harmonics seems ...
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1answer
302 views

Deriving the equation of motion for a rigid system

I want to derive equation of motion for the system shown in picture. How do I choose a generalized coordinate in order to calculate kinetic and potential energy of the system? I need the ...
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0answers
314 views

Difference between three mutually complementary methods: Raman, Infra-red spectroscopy and inelastic incoherent neutron spectroscopy?

When I read the wiki on Raman spectroscopy, I found a paragraph explaining what system is suitable for using Raman and what others do not. It provide two other method as shown in title: infrared ...
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1answer
607 views

At what temperature does the vibrational degree of freedom becomes significant for an ideal diatomic molecule?

For ideal diatomic molecules such as $\text{H}_2$, $\text{N}_2$ and $\text{O}_2$, at what temperature does the vibrational degree of freedom significantly contributes to the calculations such as that ...
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3answers
656 views

Similarity between Schrodinger and Euler-Bernoulli equations - any possible physical meaning?

I noticed a long time ago the similarity between Schrodinger equation and Euler-Bernoulli beam equation. Namely, Euler-Bernoulli equation is equivalent to the system of Schrodinger equation for a free ...
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2answers
436 views

How is frequency related to kinetic energy?

Does producing higher frequency waves require more energy than their low frequency counterparts with same amplitudes? For example, in electronics, would a 500 kHz wave require higher voltage to ...
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3answers
337 views

How to model vibration damped by applied/contact force?

I am computer science student and I am working on a project which needs to know how the vibration of phone is damped by applied force (when human touches the phone). I have read many articles about "...
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1answer
30k views

Tension of a string, based on Hz, string-weight and string-length [closed]

I’m not a physics student. Instead I have an electric bass guitar :) I know my strings vibrating-length: 0.800 Meter I know the total weight of this length: 0.016575 Kilo I know my strings resonant ...
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5answers
2k views

Why do tall buildings have low resonant frequencies?

I know that tall buildings have low natural frequencies, hence they're more vulnerable to earthquakes, but why do they have low natural frequencies?
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1answer
67 views

Is it possible to determine when an accelerometer is in a vibrating state compared to a non-vibrating state?

I would like to know if so, how raw 3-axis accelerometer data could be analyzed and manipulated real-time to register periods of vibration. The device being used has a max sample rate of 62Hz (I ...
2
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1answer
172 views

What determines the rate of vibration decay of a metal?

Suppose we have a tuning fork in a vacuum and strike it. Is there anything in the theory of metals that would predict that the tuning fork's vibration amplitude would decrease with time. Put another ...
2
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1answer
27k views

Degrees of freedom in a diatomic molecule [duplicate]

We know that a monatomic compound can only have 3 degrees of freedom as we can consider it to be a point mass. However now that we consider a diatomic molecule, there are 3 degrees of freedom in ...
2
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3answers
18k views

Any scientific basis behind “crystal energy”? [closed]

I always hear people talking very loosely about the terms "vibration" and "energy" in relation to crystals. Is there any scientific basis in "crystal energy" or is it purely metaphysical ...
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1answer
85 views

Energy corresponding to the peak of velocity power spectrum

I ran a MD simulation for a number of N molecular hydrogen. I used the velocity time history of system for each atom and subtract the velocity of center of mass of each molecule from the velocity of ...
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2answers
78 views

Undamped oscillations of sound wave

I read in google that When we hit some metal or object, then a sound is generated by that object. If we hit that object with more force, then we can hear a sound of more amplitude than previous one ...
2
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1answer
272 views

How long does it take to enter the steady state response in forced vibration?

According the basic theory of forced vibration[1], before entering the steady-state response, there is a short duration for so-called "transient" state vibration. I'm wondering how long is this "...
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1answer
71 views

In a lattice, what, technically, are random (thermal) atomic motions?

I'm familiar with normal modes and their periodic nature. And I know that the term 'independent mode' is used to describe how each individual atom in a lattice can move (degrees of freedom). But, ...
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1answer
1k views

The “potential energy” degree of freedom?

I'm reading Schroeder's "An Introduction to Thermal Physics" and he mentions the vibrational degrees of freedom of a diatomic molecule: A diatomic molecule can also vibrate, as if the two atoms ...
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0answers
84 views

Are there lattice waves/vibrational modes in materiels at room temperature and above?

The following excerpt is from: http://encyclopedia2.thefreedictionary.com/Lattice+Vibrations 'At room temperature and above, most of the thermal energy resides in the waves of highest frequency. ...
2
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2answers
171 views

How can the choice of wood make a good violin?

We always hear about some really fine and expensive wood that is used to make guitars, violins and other musical instruments. What's the physics behind this? What parameters (e.g. bulk modulus etc.) ...
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2answers
201 views

Could it be that all energy is seeking ground? [closed]

Edited version. If an electrical charge like a lightning bolt seeks ground (think of a lightning's rod's purpose), and if all matter is seeking ground (gravitational pull), and if all energy and all ...
0
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1answer
539 views

When do we use LQR controller and LQG controller?

I have to conceive a controller to my mechanical system to delete the problem of vibrations, but I don't know when we use LQR controller and LQG controller.
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1answer
40 views

Can colour be synthesized from frequency?

Given the frequency of a mechanical vibration in the audible range, one can synthesize the sound on a computer. For example, I ask "what does 440Hz sound like?" and I can listen to this frequency as ...
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0answers
44 views

Creating a structural dynamic model using only modal test data

Short version: Suppose I excite a vibrational response in some structure and measure its mode shapes and natural frequencies. Is it possible to create a structural dynamic model of the structure ...
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1answer
573 views

Car window vibrating noise

I was going to ask a question similar to: Why, when one opens 1 car window, does that noise occur? but saw that it was already asked and answered very helpfully. However, there are a couple other ...
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1answer
354 views

Problem with the Cooley-Numerov Method for Solving the Radial Nuclear Schodinger Equation in the Born-Oppenheimer Approximation

I have been trying to implement a solver for the radial nuclear Schodinger equation in the Born-Oppenheimer approximation using a similar method to R. J. Le Roy's LEVEL program[1]. I have as input a ...
3
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1answer
74 views

Textbook explanation of the resonant frequencies of molecules

An online source stated that molecules have resonant frequencies and then vaguely said that university textbooks should be consulted for more information. Another source contradicted the first in ...
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1answer
9k views

Fundamental frequency of a material and its Young's modulus

I wonder if there is a connection between fundamental frequency and Young's modulus of a material. For example, how to calculate the Young's modulus of a glass bar by knowing its frequency spectrum?
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3answers
3k views

Extra vibrational mode in linear molecule

When calculating the number of vibrational modes for a molecule, the formulas differ for linear $(n = 3N - 5)$ and non-linear $(n = 3N - 6)$ molecules, where $n$ is number of modes and $N$ is number ...
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1answer
145 views

Parabolic polarization of a hanging chain

When a chain hangs between two short posts, I can use my hand to oscillate it up and down in a standing wave. It's easy to demonstrate three of the possible normal modes, at the fundamental frequency ...
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1answer
125 views

Does the significance of frequency domain imply the resonance?

Two mobile phone, A and B, are placed on the top of a wooden desk without direct contact, the gap between these two phones is about 5 centimeters. When A is vibrating, e.g., a call comes in, a time ...