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1answer
108 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 ...
0
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0answers
19 views

Derivation of differential governing equation of Hartnell governor? [on hold]

I tried to derive the differential governing equation using energy conservative method and newton's second law, but I came up with very large and complex equations, even with assumption of small angle ...
-1
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1answer
34 views

Vibrations of a string [on hold]

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 ...
1
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0answers
25 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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0answers
25 views

3D wave equation of a 3D object [on hold]

For an example I have to derive wave equation of a sphere, x^2 +y^2 + z^2 = r^2 and its solution (wave function). Boundary condition can be anything. I like to know about eigenvalue and its use at ...
1
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1answer
24 views

looking for a technique for conducting experiment [on hold]

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 ...
2
votes
1answer
27 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 ...
5
votes
3answers
390 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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0answers
33 views

Is there any solution manual to A.P. French's 'Vibrations and Waves'?

I'm trying to work through A.P. French's Vibrations and Waves. Unfortunately, I can't check the details of my solutions since the solutions aren't given with the textbook. Does someone know where I ...
0
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1answer
361 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?
3
votes
1answer
122 views

Degenerate vibrating modes of a metal plate

My question is based around this video: https://www.youtube.com/watch?v=1yaqUI4b974 The video shows sand settling in vibrational nodes of a plate at certain resonance frequencies. It appears that ...
4
votes
1answer
296 views

Equations of motion of displacement field

We have an action: $$S[\boldsymbol{u}] = \frac{1}{2} \int dt \int d^3x \left\{ \mu (\frac{\partial u_{i}}{\partial t})^{2} - \nu (u_{ii})^{2} - \rho(u_{ij})^{2}\right\} $$ Where $u_{ij} = (\partial_{...
17
votes
1answer
629 views

Vibrational anharmonic coupling and noise-induced spontaneous symmetry breaking in a hexagonal finite mechanical lattice

Happy holidays, everyone! The following is part question, part visual gallery, and part classical mechanics problem. Inspired by snow over the weekend I began simulating the vibrations of the ...
1
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2answers
13 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 ...
0
votes
1answer
26 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 ...
1
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0answers
31 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?
3
votes
1answer
1k views

Spring system - 3 DoF system and its properties while changing stiffness

I was given the attached 3 degree of freedom spring system with the purpose of analyzing it. I came up with the following equation of motion and then I ran Matlab to calculate the corresponding ...
1
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0answers
34 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 ...
0
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0answers
21 views

Overtone Transition Probability

For an anharmonic potential, like the morse potential, higher order transitions (overtone) with $\Delta n=\pm2,\pm3,..$ are allowed. How do I calculate the probability $P$ for such transitions? My ...
6
votes
1answer
276 views

Finding the components of the tensor for potential and kinetic energy

I have a rather poor understanding of what a tensor is, but enough to apply it to the biggest part of the classical mechanics I'm studying. However, I've run into a small problem while studying "Free ...
3
votes
2answers
52 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{\...
1
vote
1answer
295 views

A moving brush on a vibrating surface

Hi group, I am a HS student in China preparing for a regional Young Physicist Tournament even. We are very puzzled about why would there be such movement. We would be grateful to see any inspiring ...
0
votes
1answer
40 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
1k 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
60 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 ...
-1
votes
2answers
756 views

Frequencies of Matter [closed]

Is it theoretically possible for physical solid matter to vibrate at a high enough frequency to become imperceptible to vision and move through other solid matter?
0
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2answers
70 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
25 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 ...
1
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2answers
154 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 ...
0
votes
0answers
8 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 ...
0
votes
2answers
58 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. ...
5
votes
0answers
71 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 ...
1
vote
1answer
49 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 ...
0
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0answers
30 views

How to get the vibratonal frequency of a bond using FFT of velocity autocorrelation function?

I guess there is some errors in the way I am calculating VAC since I ma ending up with a peak whose frequency is two times the actual frequency. I ran an MD simulation long enough with 60 molecules of ...
0
votes
1answer
117 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?
1
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0answers
26 views

How can frequency of waving in water change the direction 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 moves away from the vibration ...
1
vote
1answer
47 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.
1
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1answer
97 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 ...
0
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0answers
38 views

Does frequency of a vibration wave of a cantilever depend on its deflection?

cantilever= a beam fixed at one end only deflection is the initial displacement of the free end. the beam is let go when the free end reached its position it will vibrate, does the frequency of ...
0
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0answers
44 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. ...
3
votes
3answers
133 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 ...
1
vote
2answers
287 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 ...
1
vote
1answer
32 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)
0
votes
2answers
87 views

Why doesnt steady flow of air create sound? [closed]

When one exhales air by twisting the lips appropiately , 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 ...
3
votes
1answer
53 views

Amplitude at successive wavefronts?

Consider spherical waves emanating from a point source initially the amplitude is A, as wave travels forming wavefronts will the amplitude of each point in all the secondary wavelets be the same and ...
5
votes
1answer
168 views

To what degree does guitar construction affects the vibration of the strings?

There's an old debate going on in the guitar community about how much does wood choice and body shape affect the sound of an electric guitar. No one denies that there's a difference acoustically (how ...
1
vote
2answers
47 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 $...
0
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0answers
26 views

Natural Frequencies determination using F.E.M analysis - Damping ratio

Good day. Assume a 3d underwater tether problem, which is modelled using FEM analysis. Global equation, after assembling terms associated with corresponding elements to a single entity, should look ...
1
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2answers
71 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 $Md_tx_2(t)+Cx_2(t)+Kx_1(t)=b(t)$. ...
3
votes
2answers
111 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 ...