Questions tagged [vibrations]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0
votes
0answers
6 views

Noise generated by ball impacting a rigid obstacle

How can I estimate the noise of an elastic non-deformable ball that hits an elastic plate that is simply supported?
0
votes
0answers
32 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}\...
0
votes
1answer
30 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 ...
2
votes
1answer
214 views

Are acoustic phonons always the lowest energy vibrational modes in solids?

In solids with unit cells containing more than one atom, the normal modes show acoustic and optical branches. The number of optical branches is proportional to the number of atoms in the unit cell, ...
0
votes
0answers
12 views

Obtaining damping $c$ and spring $k$ with a $F(x)$ and $E(x)$ curve

I'm having a hard time finding c and k of a suspension system, having at my disposal three curves: F(x), Energy(x), Energy(F). Is it possible to find them with just the three curves?
0
votes
0answers
22 views

Lumped mass model of rotating engine crankshaft [closed]

My objective is to model a rotating crankshaft as a lumped mass model. This way, I can predict the stress at points along the crankshaft, using as input the force acting on each piston as well as some ...
0
votes
1answer
161 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. ...
1
vote
0answers
38 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
32 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 &...
1
vote
2answers
364 views

Why does a longer string vibrate longer before the damping brings it to rest?

While performing string vibration experiments under the boundary condition that both ends are fixed, I observed that the damping of the wave is much larger when the size of the string is smaller and ...
1
vote
2answers
259 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 $\...
2
votes
1answer
288 views

What is the difference between the dipole in IR and Raman vibrations?

In order for a vibration to be IR active, there must be a change in the dipole moment ($\mu$) of the molecule, which is given by: $\mu$ = $\sum$ q * r Where q is the charge magnitude and r is the ...
0
votes
1answer
62 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
113 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
votes
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 ...
0
votes
1answer
13 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 ...
-1
votes
1answer
37 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 ...
5
votes
1answer
41 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 ...
5
votes
2answers
1k views

What actually is the wavevector in the context of phonons and lattice vibration?

When we deal with Electromagnetic waves the wavevector has the meaning that it encodes the information about the direction of propagation, together with the wavelength. In Quantum Mechanics, the ...
2
votes
1answer
115 views

How is temperature related to quantum vibrational states of molecules?

When a molecule of greenhouse gas absorbs a photon of long wave infrared radiation it is boosted to the next allowed vibrational state. The vibrational state, as I understand it, involves deformations ...
0
votes
0answers
24 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 ...
5
votes
3answers
464 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
0answers
15 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
36 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
71 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 ...
26
votes
3answers
24k views

Theory behind patterns formed on Chladni plates?

In this video of vibrating Chladni plates we can see small sand particles align themselves into different interesting patterns (also shown in the image below) which correspond to some particular ...
2
votes
2answers
226 views

Can you vibrate an object and split its molecules?

Let’s say I have paper (or, I don't know, any other material). Can I with some sort of device vibrate the molecules of those atoms so fast that they separate, and as a result I don’t have paper ...
0
votes
1answer
326 views

Is a bending wave transverse or longitudinal?

A bending wave in a metal bar or string is simply called a transverse wave because the macroscopic oscillation is transverse. However, paradoxically, in a frame co-moving with the atoms, the atoms are ...
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
1answer
52 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 ...
0
votes
0answers
30 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
votes
2answers
701 views

What is the difference between sound and vibration?

As far as I know, the only difference between sound and vibration is that sound propagates but vibration does not. In most cases, they are the same. Please help clarify these concepts.
2
votes
1answer
351 views

Sound - for purposes of vibration

What is the best way to distribute noise from more than one source (I'm envisioning a system with many), within a dome, with the ground as its primary target, at optimal frequencies and volumes to ...
5
votes
1answer
437 views

Energy Conservation of waves at a boundary

Consider a wave traveling on a string with velocity $\upsilon$ and mass density $\rho$ having unit length so that the mass of the string is $\rho$. Considering the string to be a simple harmonic ...
1
vote
2answers
715 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". ...
4
votes
2answers
79 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 ...
0
votes
1answer
157 views

Infinite string attached to a spring [closed]

I'm trying to solve a problem related to waves on a string. Say I have an infinite string, with tension $T$ and mass density $\mu$. To the string, at $x=0$ (seeing as it's infinite, the specific ...
0
votes
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 ...
0
votes
1answer
82 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
781 views

Chladni Patterns [closed]

I'm trying to make a simulation for Chladni plates the diagram above shows the patterns on rectangular plates, and relates them to 2 values (n, m) many of the explanations suggest that (n) is the ...
1
vote
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 ...
2
votes
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 ...
0
votes
2answers
251 views

Difference between Phonons and heat?

1, if these two were the different then how we differentiate with one another?. 2, if these two were the same, then what is really vibrating?, atom in the lattice or electron in the atom or the bond ...
0
votes
2answers
144 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 ...
2
votes
1answer
428 views

Why can't resonance occur when an object is forced to vibrate (in simple harmonic motion) with a frequency other than the natural frequency?

As far as I understood forced vibrations, after a point of time steady state is reached i.e. the body oscillates in accordance with the applied force irrespective of the force frequency (may be other ...
8
votes
3answers
393 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
0answers
36 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 ($...
0
votes
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
votes
0answers
32 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 ...