# Tag Info

59

I get the same thing reheating some discs of glazed carrots. And there are several videos of folks doing this intentionally with grapes. An article published last year in PNAS says this will happen with almost any pair of similarly-sized object with sufficient water. The shape of the pairs appears to set up a resonance that concentrates the electric field ...

10

@BowlOfRed hit on it solidly. The noodles are acting as waveguides, because of their size and shape. Where they meet, a contiguous surface is created, but with a much higher resistivity, as it's a narrow point contact. Based on a table of refractive indexes and a table of frequency/wavelength, this effect would be especially effective when the total length ...

4

So resonance requires three things: An oscillator—a system which has some inertia and some restoring force, usually able to contain energy with some sort of characteristic frequency of stable oscillations. A driving force—an oscillation at a fixed frequency that is adding energy into the system. Dissipation—a drag force like friction that is removing energy ...

4

The "unique" feature of the design of crotales is the relatively big solid central cylinder, which faces down when playing them, and therefore isn't easily visible. That is much more rigid than the mounting of a typical drumkit cymbal, so all the internal energy in the crotale gets converted (slowly) into sound, rather than wasting energy shaking its ...

4

0) Try to get the book "The physic of musical instruments" by Fletcher and Rossing. It has almost everything you may need clearly explained. Material, you want one with low internal damping, that mean, low internal wasting of energy. The damping coefficient varies a lot between metals alloys and treatments. Bronze is among the best; soft steel is quite bad....

3

Prime numbers are generally used to reduce the magnitude of resonances. These occur in a non-linear multi-frequency system when two of the frequencies $\omega_1:\omega_2$ match at a ratio $p:q$, where $p,q$ are comprime integers. For simplicity, you can think of a minimal example of such a system as two (non-linear) oscillators that are coupled with a ...

3

In trying to answer this question I came across a lot of interesting phenomena related to primes. This is not a very detailed answer but will hopefully I can share the intuition and feel of the concepts involved. The phenomena we are dealing with is resonance. In any machine, there are several parts. Each part has some resonant frequency(a natural ...

3

Acoustic waves reflect off of open ends because right at the open end, there is a sudden impedance discontinuity, and anytime you have one of those, you'll get a reflection of the impinging wave. It's easy to visualize this for the case of a tube with a closed end, which represents an extremely high impedance: the incoming pressure wave piles up against ...

3

In a vibrating string, the inertance arises from the mass per unit length of the string. The compliance arises from the string's elasticity, or "stretchiness". The energy storage in the inertance (because of its velocity) goes to zero at the moment of peak displacement of the string, at which point the energy storage in the stretch of the string goes through ...

3

In my opinion, your instructor has no in-depth understanding of resonance, as he mentioned in his statement about merely memorizing a statement from the author that he was using. Kinetic energy increases quadratically and potential energy increases linearly, but both energy forms increase monotonically, meaning that there is nothing cyclic about them. For ...

3

I'm "fairly confident" that the more esoteric explanations are overly so. Voltage is induced in closed conducting paths in an RF field (here a complex E-M field with various nodes due to the cavity but that is not a major factor). AT points of contact the resistance is high and the flowing current creates "i squared R" heating. (Power dissipation = ...

3

The claims you've linked to have no support within modern science, and they never have. Those frequencies are not "received" by any specific part of the human body, and there is not a shred of evidence that they will have any health effects above those of a placebo. If you don't believe this, go ask them to point you to the clinical literature (controlled, ...

2

Is this simply due to the air distortion taking advantage of a taught string’s potential energy? No. The "air distortion" is energy. More specifically, the sound waves in the air transport energy from your voice box to the body of the guitar, and then the body of the guitar couples that energy to the strings. The vibration of the strings is powered ...

2

This is a typical resonance phenomenon. In general, a resonance is characterized by a resonance frequency, and a quality factor. The resonance frequency tells you, at which frequency the resonance can be excited. In your case, if you produce a sound at 440 Hz with your vocal chord, you hit the resonance frequency of your guitar a-string. The quality factor ...

2

If your oscillating function is of the form $e^{i\omega t}$, a phase shift looks like $e^{i(\omega t+\phi)}$, which can be rewritten as $e^{i\omega t}e^{i\phi}$. Now, recall that $e^{i\phi}=\cos\phi + i\sin\phi$. A 90 degree phase shift corresponds to $\phi=\frac{\pi}{2}$. Thus, $e^{i\frac{\pi}{2}}=\cos\frac{\pi}{2} + i\sin\frac{\pi}{2} = 0 + i = i$...

2

Try to get your hands on the book "The Physics of Musical Instruments" By Fletcher and Rossing. All those issues are well discussed there; many physicists have digged on those subjects. Short summary for your questions: Violins and guitar bodies use a vast array of tricks to amplify the sound. A vibrating string, by itself, radiates as sound only a small ...

2

Let's start with the experimental facts. Here are some Fourier power spectra that I recorded of myself singing the vowel "ah" with air (top) and helium (bottom) in my lungs: The was with me attempting to do the same thing with my vocal tract in both cases. The two sounds clearly do not differ much in the spacing of the "picket fence" of harmonics, which ...

2

The Ritz paper is pretty in depth but the simple take away is this formula for integers m and n plotted where it implicitly equals 0.

2

It's very important to learn about the phase variation of the response through the resonance - I feel that is not usually appreciated when encountering harmonic oscillators for the first time. Here is the equation of motion for the displacement of a driven harmonic oscillator: $m\ddot{x} + 2\gamma \dot{x} + kx = F(t)$ where the three terms on the left-...

2

The first system that you mentioned is the LC circuit, which I will take to be the series circuit. Let us review this, as we will compare it to the string equation later. The governing differential equation is $$L\ddot{I} + \frac{1}{C}I = 0 \ .$$ $$\ddot{I} = - \frac{1}{LC}I \ .$$ I have used the compact notation for time derivatives, but the equation ...

2

While Pythagorean tuning is a system of musical tuning, Schumann resonances are a set of spectrum peaks in the extremely low frequency (ELF) portion of the Earth's electromagnetic field spectrum, so perhaps you could elaborate on how you might use a combination of Pythagorean tuning and Schumann resonances for instrumental tuning? However, for physical ...

2

At the position of the vibrating source the amplitude of the oscillation of the palte at that position is fixed by the amplitude of the vibrating source. So with source in one position there may be a node at another position on the plate. Moving the source to the position where there that node was before would mean that it was no longer a node and so the ...

2

Yes and no. It essentially depends on what precise definitions you choose to use for several fuzzy terms in your question, but the generic answer is mostly no. The reason is that ring resonators' whispering-gallery modes can also include radial excitations, which roughly look like this: These radial excitations take on exactly the same role as higher modes ...

2

They may in special cases, but this is by no means a rule, and most certainly doesn't hold for all cases. As I'm a firm believer in concrete examples, I'll illustrate this with the following simple case of two blocks, each of mass $m_1=m_2=m$, connected to walls and each other by Hookean springs (which are harmonic oscillators) of spring constant $k$, as ...

2

I believe the question can be rephrased (more clearly) as follows: "when we collide two glass balls (or two steel balls), we hear multiple collisions. The intervals between collisions change from long to short. Why?" Take a look of this video https://www.youtube.com/watch?v=k1id4a4EU4M (Pay attention to time 1:01) when he casually collided the balls you ...

2

Ever heard about antiresonance? As the name suggests it is opposite of resonance, which is hardly taught in elementary classes. Considered two coupled oscillators where one is forced with say a harmonically driven force and other with without any forcing, just like the building and the TMD system, where the building is forced by say some seismic vibrations. ...

2

There are several questions here. First, the factors that determine the resonance frequency of a piece of pipe are 1) the speed of sound waves in the pipe, 2) the length of the pipe, and 3) the nature of the termination of the undriven end of the pipe. 1) and 2) tell you how long it takes a sound wave to travel from one end of the pipe to the other and 3) ...

2

When sound is produced by the wind blowing past objects in its way, the usual mechanism is called vortex shedding and was studied by Von Karman in the late 1940s. In his model, sound waves are produced when the wind blowing past (for example) a wire toggles between blowing over the upper surface and the lower surface. This cyclic excitation gets coupled to ...

1

Gears should have (co)prime number of teeth to provide even wear (https://en.wikipedia.org/wiki/Prime_number#Computational_methods), but I don't see why a wheel needs to have a prime number of spokes. On the other hand, it seems that an odd number of spokes might be preferable for manufacturing (https://www.quora.com/Why-do-car-wheels-tend-to-have-an-odd-...

1

There will be a standing wave whenever you terminate a transmission line with a mismatched load. The line is resonant when the standing wave has a minimum or maximum of amplitude at the input (or feed point) of the line. If the termination is short, open, or has purely real impedance, then this occurs when the line length is $L = n\frac{\lambda}{4}$ for ...

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