# Questions tagged [vibrations]

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### 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 ...
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### What is the frequency associated to the orbitals within an atom?

I was told that there's a vibrational frequency associated to the orbitals within an atoms, but it is a frequency related not to a classical vibration. What Hz frequencies would these be?
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### Models for vibrations and stress waves generated due to impact?

Say that a small metal ball impacts a long thin cylindrical rod from above (let's say height of around 10 cm) in an elastic collision and causes stress waves to propagate left and right from the point ...
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### What is the frequency of each of the moving electrons in a DC current?

I know that the DC current has 0 frequency. But what about each individual moving electron that makes up that DC current? Of course there has to be a frequency as all moving electrons are vibrating at ...
23k views

### Vibration of Quartz crystal

What does it mean when we say quartz crystal vibrates.it is very strange to read that a particular solid vibrates with period of 10^(-6) seconds.does it mean something else when it is written quartz ...
600 views

### The spring of air: Why does a piston undergo SHM when it is displaced lengthening the air-column inside a cylinder filled with air?

Let there be a cylindrical tube, closed at one-end, with a well-fitting but freely moving piston of mass $m$. [. . .] The piston has certain equilibrium position. If the piston is moved a distance $y$ ...
263 views

### How does any vibrating object generate sound?

We all know that vibration is the cause of sound generation. But here my question is, Internally what happens in vibrating object which creates sound? I guess, generation of sound will be some where ...
143 views

### Finding the frequency of vibration of part of a system

The setup: 4 spheres of diameter $d$ are suspended on a horizontal plane (magically). They are arranged in a square with length $l$ (the vertices are correspondent to the sphere's centers). The ...
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### Amplitude Modulation in dispersive mediums

I'm reading the book "Physics of Waves" by Georgi. In section 10.2 he says that to send a signal through one-dimensional dispersive mediums where the dispersion relation is not $\omega(k)=vk$ ($v$ the ...
794 views

### Is molecular vibration just phonon modes for a single molecule?

I'm reading about Raman Scattering, of which a big part is measuring the energy lost to/gained from Molecular Vibrations. I wasn't totally clear on exactly what is "vibrating" in vibrational modes (is ...
351 views

### Definition of mechanical impedance

Mechanical impedance is in the simplest (yet common) case defined as: $$Z_m = \frac{F}{v}$$ where $F$ is force (let's assume 1D case) and $v$ velocity of the object (let's assume point of mass). ...
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### Energy dissipation in damped oscillator (not driven by any external force)

If I have a damped oscillator (with no driving force), the energy of the oscillator will decrease like: $$E(t)=E_0e^{-\gamma t},$$ where $E_0$ is some initial energy and $\gamma\in\mathbb R^ +$. We ...
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### Vibrating Objects Part 2

Since I have an answer to Vibrating Objects, I am asking a part two about much faster vibration. What about vibrating an object at 1 THz or higher? What methods can be used? How much energy is spent.
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### Vibrating Objects

I'm not sure if this belongs in Engineering, but if it does, please migrate the question. What methods are used to vibrate objects extremely quickly? What are the most common?
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### 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 ...
2k views

### Simple pendulum cartesian coordinates

I'm reading Vibrations and Waves from French. I don't understand the following approximation when considering the simple pendulum: Referring to the last figure if the angle $\theta$ is small we ...
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### What is the effect of vibrations on an object's properties?

What do vibrations do to an object's properties? By making an object vibrate at a high frequency (compared to its static state) would vibrations: Increase or reduce its moment of inertia? Increase ...
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### Effect on Q factor and resonant frequency when scaling down a damped oscillator to micro / nano scales

I've always just accepted that as you scale down a mechanical system the frequency and Q factor both increase. But how exactly do they scale? Linearly? With the square of reduction in size? Or maybe ...
3k views

### In counting degrees of freedom of a linear molecule, why is rotation about the axis not counted?

I was reading about the equipartition theorem and I got the following quotations from my books: A diatomic molecule like oxygen can rotate about two different axes. But rotation about the axis down ...
444 views

### What is the relationship between vibration of the field and quantum fluctuation?

Consider a free field like the KG equation. I see that why $$\tilde \phi(\mathbf{p},t)$$ a momentum-dependent quantity, is an oscillator, vibrating at a frequency because when we apply the Fourier ...
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### Why do objects have resonance at natural frequency?

What actually is a natural frequency for an object and what makes it vibrate with increased amplitude when coupled with an external oscillator that matches the natural frequency?
496 views

### How to reduce vibration on aluminum quadcopter? [closed]

I have an aluminum quadcopter with that's made of thin aluminum and its really flimsy. And there is lot of vibration when I fly it. My question is, if I make the frame stiffer so it doesn't bend, will ...
149 views

### Non-linearity of a guitar pickup

I basically understand induction and why a pickup generates a signal. (From: http://www.brighthubengineering.com/consumer-appliances-electronics/64277-the-physics-behind-the-electric-guitar/) What ...
1k views

### Natural Frequency of an object and the phenomenon of resonance!

I have read about the term natural frequency in quite a lot of places. But I haven't found an explanation as to what is vibrating. It was pretty awkward when I couldn't clearly answer my little sister ...
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### Modelling an Inelastic Collision

I've attempted to model the inelastic collision between a moving mass and a large stationary object, e.g. dropping an ball on the floor, for analysing the approximate kinematics and heat dissipation ...
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### What affects the period and the frequency of a longitudinal vibration?

In a lab experiment, our objective is to observe the characteristics of longitudinal waves/vibrations. If we changed the mass and amplitude, I feel that they either affect the period and frequency of ...
480 views

### Air Presure and Air Velocity from speaker

How do I determine/calculate the air pressure emitted from a speaker ? And how to determine the velocity of air from the sound air pressure ?
1k views

### When an aircraft flies over, glass window vibrates…Infrasound?

When an aircraft flies over, my big glass window vibrates, making a ticktack beating. Its frequency sounds low, less than 10 beats per second actually. I'm wondering about the mechanism of this ...
127 views

### Isolate an electronic drum from the ground

Please note that I know nothing about this part of physics, so sorry if I make some mistakes. Drum is an awesome instrument, yet it can easily make your neighbours very angry.The vibrations caused by ...
138 views

### Coupled ODEs that model a quad rotor

I am working on modeling the vibrations of a quad rotor. The arms that support the rotors are fixed to a center plate; that is, it is pretty much a cantilever beam with an end load. Since this is the ...
85 views

### Vibrational modes of a plate

What is the distinction between thickness-extensional, contour-mode/Lamb wave, in-plane shear, and the flexural modes of a plate, and under which conditions are each mode excited? Pictures for ...
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### Is there always motion, when force is present? Is all motion vibration?

Even when you are seated in a chair, the chair is pushing up on you and you down on the chair (manifesting in the form of ~650N). While there is no obvious observable motion, is it not possible that ...
2k views

### Why does the pitch of a container being filled with water increase? [duplicate]

I wonder about this. If you pour water in a closed tank, it makes a noise. I have noticed that as the container becomes more and more full, the pitch of this noise also increases. Why is that? I do ...
4k views

### What does degrees of freedom mean in the context of vibrations?

If you have an $N$ degrees of freedom system what does this mean? What is the difference between a 1 and a 2 degrees of freedom system?
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### What equation can be used to solve an ideal string/membrane in a non-vacuum medium?

I'm interested in the eigenmodes of the membrane for various mediums, such as vacuum, air, water, etc., which impose a damping effect on the membrane. This cannot be done by merely changing the value ...
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### What is the meaning of pre-tension for a stiff membrane?

On one hand, I know that the tighter a drum head is stretched, the higher its natural frequencies. This relation is given by: $$f_{ij}=\frac{k_{ij}}{2\pi R}\sqrt{\frac{T_0}{h\rho}}$$ where $k_{ij}$ ...
57 views

### Can an axisymmetric solution produce antisymmetric eigenfunctions?

I'm solving a vibrating membrane. In order to simplify my calculations, it's tempting to assume axisymmetric behaviour. If I solve an axisymmetric problem, am I going to lose all the antisymmetric ...
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### Finding the one-dimensional wave equation the vibrating string

It's a relatively simple problem and I've been able to solve it in a different way before, but the current book I'm learning from left me with some questions: After a few idealizations we get the ...
348 views

### Meaning of ideal membrane

I'm studying from a mathematical point of view the bidimensional vibrating membrane. How can I define an ideal membrane? What are the assumptions when I say 'ideal'? Thanks!
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### Transfer function of vibrating string [duplicate]

I need to find moments of vibrating string and I think that transfer function could be useful for this, but I don't know transfer function of vibrating string. Can someone give me some idea how to ...
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### Moments of vibrating string

I have to calculate first 10 moments for vibrating string with damping, but I don't know how to do it. I read about moments and in definition they mention linear system $$x'=Ax+Bu, \qquad y=Cx$$ with ...
10k views

### “Magic” Speed to Drive Over a Speed Bump: Myth or Reality?

A somewhat controversial aspect of speed bumps (sleeping policemen for those in the UK) is that they arguably cause more loss of life than they prevent by acting as a hindrance to emergency response ...
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### Why sound does not heat up the air?

Both thermal energy and air are propagated through vibration of particles so why sound does not heat up the air e.g loud musical instrument does not generate much heat ?
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### Difference between sound and heat at particle level

If heat (or thermal energy) are vibrations of particles and sound is a wave that is propagated through medium e.g vibration of air particles, what indicates if vibration of particles will be perceived ...
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### Does the speed at which sound travel depend on the volume (amplitude) of the sound?

Lets say you have a plank is you hit it once and get t time if you hit is 2x as hard will it travel t/2? will it be the same or will it travel only slightly faster?
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### 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 ...
110 views

### What happens to the energy?

if we make a bell ring in a vacuum room for 5 mins. And then open the door, will be able to hear the sound? If no sounds vibrations are emitted to the environment what happens to the energy that ...
345 views

### Vibrationing molecules/atoms and the effect

If the molecules/atoms of a solid object vibrate quickly enough, would the way a human eye perceives that object be changed? Would the object appear to "flicker" or have almost a transparent look to ...