# Tag Info

## Hot answers tagged resonance

45

If there were only one prong (imagine holding a metal rod in your hand), then the oscillation energy of the prong would quickly be dissipated by its contact with your hand. On the other hand, a fork with two prongs oscillates in such a way that the point of contact with your hand does not move much due to the oscillation of the fork. This causes the ...

36

I am by no means an expert in tuning fork design, but here are some physical considerations: Different designs may have different "purities," but don't take this too far. It is certainly possible to tune to something not a pure tone; after all, orchestras usually tune to instruments, not tuning forks. Whatever mode(s) you want to excite, you don't want to ...

24

The reason for having two prongs is that they oscillate in antiphase. That is, instead of both moving to the left, then both moving to the right, and so on, they oscillate "in and out" - they move towards each other then move away from each other, then towards, etc. That means that the bit you hold doesn't vibrate at all, even though the prongs do. You ...

12

Q. How do two coupled vibrating prongs isolate a single frequency? howstuffworks.com has an article on How Tuning Forks Work The way a tuning fork's vibrations interact with the surrounding air is what causes sound to form. When a tuning fork's tines are moving away from one another, it pushes surrounding air molecules together, forming small, ...

10

There seem to be a lot of human body mechanical models, such as this one: As for applications, I have heard that sub-audio frequency vibrations have been considered as nonlethal weapons for riot control.

6

It would depend on damping effects being taken into account or not. Invoking Newton's 2nd Law of motion, a differential equation for the motion of a damped harmonic oscillator can be written (including an external, sinusoidal driving force term): $m\frac{d^2x}{dt^2}+2m\xi\omega_0\frac{dx}{dt}+m\omega_0^2x=F_0\sin\left(\omega t\right)$ Where $m$ is the ...

5

The first generation of elementary particles are by observation not composite and therefore not seen to decay. They are shown in this table of the standard model of particle physics in column I. The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column and the Higgs boson in the fifth. All ...

4

Any physics-oriented FEM solver should do this. I have only done it with COMSOL, which is proprietary and expensive, but searching Ubuntu's repository of free software turns up at least two promising candidates: Elmer and FreeFEM. I'm trying out Elmer now. http://www.csc.fi/english/pages/elmer http://en.wikipedia.org/wiki/Elmer_FEM_solver This example ...

4

I have just noticed the question. Indeed, the body does have very clear resonances. Nature has prioritised speed of movement over stability so limbs are underdamped and naturally resonant. It is likely that many rhythmic movements occur at the resonant frequency of the body parts involved (rather similar to the oscillation of some insect wings). A ...

4

The Moon moves away about four inches a year on Earth, 15 while the Earth's rotation is slowing down, which will in the distant future total solar eclipses occur stop the moon not having sufficient size to cover the solar disk. In theory, this separation should continue until the Moon takes 47 days to complete one orbit around our planet at which our planet ...

4

In an experiment in which particles are collided, a resonance is a large peak in a cross section (rate at which a process occurs) when plotted against the energy of the incoming particles. For example, when LEP collided electrons with positrons, they saw a resonance when the energy of the incoming particles equalled the mass of the $Z$-boson. Resonances ...

3

No, because in a vacuum, there is no way for the two tuning forks (I think you meant this, rather than pendulums) to communicate. The reason a second tuning fork with the same resonance frequency will begin resonating is because, physically, sound waves are hitting it at its natural frequency. Sound waves travel in a medium, so in a vacuum, there's nothing ...

3

The oscillator frequency $\omega$ says nothing about the actual oscillator phase. Let us suppose that your oscillator oscillates freely like this: $$x(t) = A_0\cdot\cos(\omega t + \phi_0),\; t<0.$$ At $t=0$ it has a phase $\phi_0$. Depending on its value the oscillator can be moving forward or backward with some velocity. If you switch your external force ...

3

The inductor and capacitor form a resonant circuit, which will pass only a specific frequency - the one you are tuning the radio to recieve. You normally tune it by making either the inductor or capacitor adjustable. edit: As described in How does radio receives signal from particular station? it's very much like a pendulum. Current flows freely in the ...

3

Both "perfectly open" (zero acoustic impedance) and "perfectly closed" (infinite acoustic impedance) boundary conditions are only idealizations that never occur in practice. For the case of the human vocal tract, they aren't even very good approximations. The "bottom end" of the resonating cavity is not, in fact, the lungs, but the vocal folds (as Georg ...

3

The first resonant vibrational mode for a string clamped at both ends looks like: You should be able to deduce the wavelength from that diagram. The second mode looks like: Both of the images above are from http://www.clickandlearn.org/Physics/sph3u/Music/Music.htm and that site will spell it out in more detail for you. If your string length is ...

3

For an account of modern instances of resonance damaging structures, see the Sketpics SE post listed by Dr. RedGrittyBrick listed in the comments. I don't know of any historians' recording of events such as you describe, so hopefully another answer can do this. As for understanding the $Q$-factor and its effect on resonance: classical resonances comprise ...

3

Why does maximum resonance occur at triple the length of air column for the previous maximum resonance? Because resonance in a pipe that is closed at one end occurs when a standing wave of air is generated within the pipe, and this can only happen if the open end of the air column is a displacement antinode (where the wave is at its max amplitude), ...

3

Re question 1: when you learn this stuff in school you usually simplify the system by modelling it as a simple harmonic oscillator so the amplitude of the system will be given by some equation like: $$A(t) = A_0 e^{i\omega_0 t}$$ where $\omega_0$ is the natural frequency of oscillation. Typically you study what happens if you apply a force that also ...

2

There's an interesting question in here if you look hard enough. First of all, there's nothing special about the resonant frequency of something made of little magnets. It might as well be a piece of ordinary string, a metal bar, or whatever. In fact I think the fact that it's made of separate little magnets stuck together would give it a much lower Q ...

2

If you have two decoupled oscillators, they satisfy differential equations $$-\frac{d^2}{dt^2}x_i=\omega^2_{i} x_i$$ where $i=1,2$. The solutions are clearly multiples of $\cos(\omega_i t+\phi_i)$. Now, consider two interacting oscillators. Each oscillator must know about the phase of the other, so the simplest dependence is to add a multiple of $x_2$ (a ...

2

OK, the simple answer: When there is a resonance in the antenna you have a coherent phenomenon. All the bands of electrons of the antenna are marching in tune. The black body radiation is an incoherent phenomenon coming from the individual atoms of the antenna. Even if the peak of the black body radiation were sitting on the resonance of the antenna it ...

2

The derivative-like line shape is a result of the use of field modulation. In order to get sufficient signal to noise, the B_0 field (large, static field) is modulated (usually at 100kHz) and a lock-in amplifier (or equivalent) is used to reject any frequencies beside 100kHz. The result of this field modulation is that the signal that is obtained is not ...

2

Real LC circuits have some resistance, which wastes some of the energy as thermal radiation, and the cycling eventually dies. I think they also have some other non-idealities that allow energy to escape as far field electromagnetic radiation, correct? What are these non-idealities? Are they independent of the resistive component? ...

2

This must be impossible, even for lady Castafiore with her earthquake voice. For a glass to break by sheer sound you need to produce a tone equal to the glass's natural frequency - the frequency at which a body vibrates with the least amount of energy. In other words: there you get the most vibration with a minimum of effort. This is also called resonance. ...

2

Vibrations begin to resonate together into sound waves we can hear. We can make the sounds loud or soft depending on how much pressure we place on finger. The pitch of the sound can also be changed by adjusting the amount of water in the glass.As you rub your finger on the rim, your finger first sticks to the glass and then slides. This stick and slide ...

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