Questions tagged [vibrations]
The vibrations tag has no usage guidance.
406
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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
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0answers
21 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 ...
-2
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0answers
24 views
Deriving the vibration formula [duplicate]
How to derive this formula, without too complicated terms as I am still at highschool. Is there any algebraic explanation for it?
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14 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 ...
2
votes
1answer
35 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
votes
1answer
66 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
17 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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29 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
51 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 ...
5
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3answers
454 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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0answers
11 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
78 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
386 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
55 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
48 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
30 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
35 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
368 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
29 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
28 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
139 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
49 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 ...
1
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1answer
91 views
Difference in Sound and Heat
What makes sound and heat distinct ?
The answer is said to lie in the fact that the former consists of vibration in an ordered fashion while the latter is not.
But why would ordered vibration not be ...
1
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2answers
120 views
Can mass be ejected from a black hole within the Schwarzschild radius?
This goes far beyond my limited knowledge regarding the physics of black holes, but my colleague told me this today:
I doubt that if I stand on the surface of a black hole - inside the
...
1
vote
1answer
111 views
Can dispersion relations be derived using Euler-Lagrange equations?
The question is long because of the demonstrations I give, but the problem is simple, so bear with me for a minute.
I am trying to derive the dispersion relation of a semi-infinite system using Euler-...
0
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0answers
39 views
Transverse vibration of triatomic molecule from Landau Mechanics Sec. 24
Transverse vibration of a triatomic molecule ABA which consists of two identical atom A and one another atom B such as $\mathrm{CO}_2$ is depicted in page 24 Sec. 24 Landau Mechanics.
The ...
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1answer
95 views
What are “vibrations” in a field in Quantum Field Theory (QFT)?
For example, in a 2013 article for NOVA Don Lincoln writes:
Everywhere in the universe there is a field called the electron field. A physical electron isn’t the field, but rather a localized ...
2
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0answers
17 views
Does putting a part under stress change its natural frequency?
It is easy to imagine how tension changes the natural frequency of a wire. Intuitively it happens with a guitar string when you bend the neck.
However, does putting a beam under stress (internal or ...
0
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0answers
19 views
Will a cantilever tube vibrate if fluid enters from its free end and flows into the fixed end?
For dynamics of a cantilever pipe with fluid flowing from fixed end towards free end, there are values of frequency for a threshold of flow velocity that gives unstable, stable and neutral systems, ...
0
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1answer
44 views
How to measure the mechanical vibration when a hammer hits a nail? [closed]
I want to know the exact location of the vibration sensor that can be placed to measure the vibrations created by a hammer hits the nail.
0
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0answers
20 views
Normal mode decomposition of a triangular hexagonal lattice
I was trying to understand and redo the methods used in a previous question:
Vibrational anharmonic coupling and noise-induced spontaneous symmetry breaking in a hexagonal finite mechanical lattice
...
2
votes
0answers
26 views
Physics of a catenary with sinusoidal motion at one end
If we have a catenary line with a mass per unit length of m with one end fixed and the other end moving in sinusoidal motion like $A.sin(\omega.t)$, how would I ...
0
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2answers
106 views
Which waves are produced during tuning fork vibration? [duplicate]
In my book, it is written that transverse waves are produced during physical motion of tuning fork. But vibration of tuning fork produces sound which are compressional in nature .
Please tell me ...
2
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0answers
26 views
vibration and movement of electric appliance
So, what I am thinking about here is a cooking mixer placed into a bowl which is turned on and left moving on its own. The bowl is such that it does not topple nor the mixer falls out of it.
Once the ...
2
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0answers
26 views
Book for electromagnetic waves and radiation
MIT course 8.03SC recommends Electromagnetic Vibrations Waves and Radiation (The MIT Press) by Bekefi and Barrett for extra reading however I am unable to find any soft copy online and its too costly ...
1
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1answer
69 views
Why are higher frequencies amplified less by filling a bottle with warmer water instead of colder water?
Out of curiosity I was trying to figure out what makes the sound of hot water versus cold water filling a bottle different, but I'm unable to find any explanation as to why such differences occur.
...
0
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2answers
65 views
The Strings have a finite size they can vibrate?
as I searched about the Strings theory I found out this explanation:
Since the strings have a finite size they can vibrate. All the known particles of nature are just different modes of vibration of ...
2
votes
2answers
55 views
What makes quartz oscillators vibrate?
I understand that the principle behind it is piezoelectricity and electrostriction (inverse piezoelectricity), but how does one make the crystal vibrate?
The only thing I can think of is using an ...
3
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5answers
292 views
What is the reason behind resonance?
At the technical highschool that I attend, the instructor said that the cause of resonance is that energies increase differently.
Kinetic energy increases quadratically and potential linearly, so the ...
0
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1answer
42 views
Heat capacity due to Phonon Vibrations
Why does the speed of sound come, in the expression of Heat capacity, from phonon vibrations?
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0answers
57 views
Faraday waves and Chladni plates
I am a High school student who's writing a research paper about Faraday waves and Chladni plates. I've been doing a lot of research on Faraday waves specifically, as there aren't many sources that can ...
0
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1answer
73 views
Optical and acoustic branch
Does a diatomic crystal posses both optical and acoustic branch simultaneously; Or, whether the vibration is either optical or acoustic?
1
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1answer
52 views
Why standing wave conditions don't include a phase difference of π
So in order to set up a standing wave on string I can set a travelling wave on it first then let this travelling wave get reflected from a fixed end and this reflected wave interferes with the ...
0
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1answer
59 views
What will happen to these colliding strings?
What happens when these two strings collide? Do they cancel each other out, pass through each other or interact in some way?
Thanks.
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0answers
71 views
sounds of polygonal ring chimes of metal
Suppose we have a number of rings, each of them is constructed from some mass of wrought iron or steel: each ring is a polygon, which I would like to suppose is constructed without welding (so they ...
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0answers
22 views
Error in FFT (Sectrum) analyzer Instrument
Recently I performed an experiment on finding the natural frequency of vertical cantilever. I used accelerometer and FFT analyzer instrument for measuring it. First I kept the accelerometer near the ...
3
votes
2answers
110 views
Are sinusoidal travelling waves also normal modes of vibration?
According to definition of normal modes, which says if all the different independent parts of a system vibrate at same frequency and their amplitude preserve a fixed ratio then such a motion is a ...
0
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1answer
40 views
Shouldn't reflection at the boundary interfere with the original wave to not give any wave?
So I have been taking a wave course, and one thing that I don't understand is how does reflection even allows normal modes of vibration. I'll try to explain my confusion:
Suppose we have a string ...
3
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0answers
55 views
Prove from first principles that a guitar string will vibrate at a constant frequency
From experience I am aware that a taught string will generally vibrate with a constant frequency. I wanted to prove this by considering the relation of distance from the resting position, and its ...
