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1answer
99 views

Two coffee beans in a cup of water + vibrations = gravity? [duplicate]

If you float two coffee beans in a cup of water that is being vibrated by your subwoofer (go to a sin wave generator online), the two beans will either be attracted to the sides of the cup or if ...
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1answer
158 views

Spring Damper System for a Vibrating Motor

Good day people of SE I have a friend that has a final year project and is stuck. He has a motor with a small weight at the end of the shaft that causes vibrations. This motor is on a thin plate. ...
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1answer
266 views

Does the frequency of a vibrating substance like a string depend on its properties or simply depend on the agent which vibrates the string?

We know that if someone vibrates a substance like a string, the string oscillates with its natural frequency. But I think the frequency depends on the rate the agent like a man's hand does vibration ...
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1answer
433 views

Why do we need hard steel balls to produce an unusual ‘chirping’ sound?

When two hard steel balls, or similar, are brought gently into contact with each other, an unusual ‘chirping’ sound may be produced.why do we need this material or shape to produce that sound?
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1answer
114 views

Duhamel formula for propagators

Let $\dot{z} = A(t)z + b(t)$ with $ z(t) \in \mathbb{R}^n$ and $A(t)$ be a linear map from $\mathbb{R}^n \rightarrow \mathbb{R}^n$. A propagator is also a linear map $P(t,s):$ $\mathbb{R}^n ...
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2answers
1k views

Can a simple pendulum be considered a simple harmonic oscillator?

Is the motion of a simple pendulum, a simple harmonic motion? It stops vibrating after sometime.
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2answers
154 views

With the phone Vibration why the whole bed vibrates

While we are lying on the bed and there is a phone placed somewhere on the bed, when the phone vibrates we can feel the vibration all over the bed, but in the scenario when we are lying on the floor ...
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1answer
45 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
201 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 ...
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1answer
63 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 ?
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2answers
139 views

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 $k_{ij}$ ...
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1answer
47 views

Vibration in a broken cylinder

The physics S.E. may be wrong for this question, but I wonder what happens to a vibration in broken, cracked, or otherwise damaged cylinder. Say you have a 1 meter long steel cylinder, you break it in ...
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1answer
635 views

How do I recover the 1D wave equation from the Lagrangian?

Consider small displacements, $y(x,t)$, of an element of a string (circled in red and shown below) from equilibrium. The force balance in the vertical direction yields: $$+\uparrow \Sigma F: ...
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1answer
264 views

What is actually a resonating vibration and resonance?

What is actually a resonating vibration and resonance? I have searched many books and made Google search too but couldn't understand it clearly.
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0answers
19 views

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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1answer
135 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 ...
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0answers
32 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 ...
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1answer
43 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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0answers
24 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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0answers
193 views

Calculate surface pressure due to forced vibrating plate using wavenumber space [closed]

My problem lies in the field of acoustics. I have a given complex velocity distribution. The velocity is the velocity in the normal direction to a rectengular simply supported vibrating plate. I now ...
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1answer
65 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 ...
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1answer
62 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 ...
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1answer
91 views

What is the physical origin of acoustic modes in a duct?

Lets deal with wave propagation in a cylindrical duct. We ask the question: "what is the general form of a pressure wave which can propagate through the duct?" In answering this, we assume that the ...
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0answers
71 views

stopping, moving of mobile phone when vibrating

A mobile phone move aside when it vibrates. How is that happening ? and most importantly is it possible to make any changes to the vibration motor to stop moving when vibrating or any other methods to ...
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1answer
28 views

Vibrational noise for scientific apparatus on a satellite

Say we're running an experiment on a satellite in some earth orbit. For example, maybe we're imaging something with transmission electron microscope or we're catching atoms in ion traps --- really ...
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0answers
60 views

Closed pipe/sound resonance sound type sound coming from mineral processing plant

I work near a very large mineral processing plant which does vibrate our building and there is also a sound/feeling very similar to the closed pipe/sound resonance that is achieved when opening a back ...
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0answers
56 views

Modeling Acoustic Lubrication

I thought about posting this question in the Biology StackExchange site but really it is just the application of my question that applies to biology not the core of the question itself. Can anyone ...
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1answer
63 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 ...
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3answers
68 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 ...
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1answer
94 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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1answer
16 views

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 ...
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2answers
39 views

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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3answers
3k views

Young's Modulus and Vibrating String Harmonics

I was wondering how Young's Modulus effects the resonant harmonics of a vibrating (string instrument) string. I know that the string's fundamental frequency is $$\frac{1}2 \times \text{Length} \times ...
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1answer
129 views

What theory is the person in this song talking about?

What he is talking about sounds interesting to me, and I would like to know more. But I need to know the name first. http://www.youtube.com/watch?v=Ogn5FrVGtAg&hd=1
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1answer
21 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
41 views

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 ...
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1answer
78 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 ...
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2answers
78 views

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 ...
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1answer
121 views

How Sound of Mobile Vibration travels through wire of Earphones

This may sound dumb, but I have been observing that, If my mobile phone is placed on the wire of my hands free (earphones) and if my mobile vibrates, I could listen the vibration from the ear plugs. I ...
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3answers
93 views

How does ultrasonic horn produce a convection current in the water?

When I was using ultrasonic horn in a beaker, I notice that there are convection currents in the beaker and stir up my substance. I don't understand why it produce water current, I thought that it ...
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1answer
2k views

Phase shift of resonance [duplicate]

For resonance to occur, is it true that the force lags behind the motion by $\pi/2$? I saw some notes written that the motion lags behind the force by $\pi/2$ which makes no sense to me. As I watched ...
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1answer
30 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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1answer
36 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
31 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 ...
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0answers
66 views

Vibrating water container problem

I am struggling with visualising and understanding the phrasing of this question - cross posted from Math stack exchange since this forum is more appropriate: "A water-filled container is ...
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0answers
18 views

How to compare natural frequencies for different pendulum-spring systems oscilating around the vertical equilibrium?

Im trying to compare the natural frequency of different pendulum oscilation systems around the vertical equilibrium. For the first case the balance of momentum is very simple and the natural ...
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1answer
26 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 ...
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0answers
29 views

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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1answer
17 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 ...
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1answer
44 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). ...