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How does a guitar work? Contents First, something about sound If you put your finger gently on a loudspeaker you will feel it vibrate - if it is playing a low note loudly you can see it moving.

How does a guitar work?

When it moves forwards, it compresses the air next to it, which raises its pressure. Some of this air flows outwards, compressing the next layer of air. The disturbance in the air spreads out as a travelling sound wave. At any point in the air near the source of sound, the molecules are moving backwards and forwards, and the air pressure varies up and down by very small amounts. The strings The pitch of a vibrating string depends on four things. The strings themselves make hardly any noise: they are thin and slip easily through the air without making much of disturbance - and a sound wave is a disturbance of the air.

The body The body serves to transmit the vibration of the bridge into vibration of the air around it. The air inside More detail and other links. Strings, standing waves and harmonics. The animation shows the interaction of two waves, with equal frequency and magnitude, travelling in opposite directions: blue to the right, green to the left.

Strings, standing waves and harmonics

The red line is their sum: the red wave is what happens when the two travelling waves add together (superpose is the technical term). By stopping the animation, you can check that the red wave really is the sum of the two interacting travelling waves. The figure at right is the same diagram represented as a time sequence - time increases from top to bottom. You could think of it as representing a series of photographs of the waves, taken very quickly. The red wave is what we would actually see in a such photographs. Suppose that the right hand limit is an immoveable wall. At the fixed end they add to give no motion - zero displacement: after all it is this condition of immobility which causes the inverted reflection.

This is shown in the animation and the figure. Strong coupling of torsional and transverse waves in a bowed string. This page is an appendix for the scientific paper: Bavu, E., Smith, J. and Wolfe, J.

Strong coupling of torsional and transverse waves in a bowed string

"Torsional waves in a bowed string" (2005, Acustica, 91, 241-246). It has sound files of the translational and rotational waves, an animation of idealised Helmholtz motion in translation and a brief summary of the paper. This figure, reproduced from the paper, shows the velocity, in time and frequency domain representation, of the transverse and torsional waves in a bass E string, bowed by an experienced string player. For comparison, the torsional wave is represented by rω, the product of the string radius and the angular velocity. Sound of the transverse wave (74k) Sound of the torsional wave (33k) Notice that both sounds have the clear pitch associated with a highly periodic signal and that, in both cases, the pitch is that of the transverse fundamental.

The animation (made by Heidi Hereth) shows idealised Helmholtz motion of a transverse wave. A brief introduction and summary. Formulating Science in Terms of Possible and Impossible Tasks. David and I have been working on this together for the past three years, and we’ve been applying it to many different problems.

Formulating Science in Terms of Possible and Impossible Tasks

So far, the two completed parts of our trying out constructor theory to see whether it can solve problems are: a fundamental theory of information within physics1; and the constructor theory of life2, which applies this new theory of information to a fundamental problem that's at the boundary between physics and biology, and has to do with how certain features of living things, such as the ability to self-reproduce very accurately, are compatible with the laws of physics as we know them.

In these two cases, you can see how switching to this new mode of explanation allows one to change the perspective and address the problems in a much more effective way. These are two examples where switching to this new mode of explanation makes all the difference. Take information, for example. One question might be how do you test constructor theory? [1] D. . [2] C. Music - Bitport.io. Brian Eno’s Reading List: 20 Essential Books for Sustaining Civilization.

By Maria Popova Deconstructing a magnificent mind through his reading diet for intellectual survival.

Brian Eno’s Reading List: 20 Essential Books for Sustaining Civilization

UPDATE: The folks from the Long Now have kindly asked me to contribute to the Manual for Civilization library — here is my own reading list. There is something inescapably alluring about the reading lists of cultural icons, perhaps because in recognizing that creativity is combinatorial and fueled by networked knowledge, we intuitively long to emulate the greatness of an admired mind by replicating the bits and pieces, in this case the ideas found in beloved books, that went into constructing it. After the reading lists of Carl Sagan, Alan Turing, Nick Cave, and David Bowie, now comes one from Brian Eno — pioneering musician, wise diarist, oblique strategist of creativity — compiled for the Long Now Foundation’s Manual for Civilization, a collaboratively curated library for long-term thinking.

Join me in supporting the Manual for Civilization, then revisit Eno’s insights on art. Tons of Albert Einstein Documents Are Now Online for Free. Einstein Papers Project at Caltech. FLP Vol. I Table of Contents. The Feynman Lectures on Physics Vol. I Ch. 1: Atoms in Motion. 1–1Introduction This two-year course in physics is presented from the point of view that you, the reader, are going to be a physicist.

The Feynman Lectures on Physics Vol. I Ch. 1: Atoms in Motion

This is not necessarily the case of course, but that is what every professor in every subject assumes! If you are going to be a physicist, you will have a lot to study: two hundred years of the most rapidly developing field of knowledge that there is. So much knowledge, in fact, that you might think that you cannot learn all of it in four years, and truly you cannot; you will have to go to graduate school too! Surprisingly enough, in spite of the tremendous amount of work that has been done for all this time it is possible to condense the enormous mass of results to a large extent—that is, to find laws which summarize all our knowledge.

Each piece, or part, of the whole of nature is always merely an approximation to the complete truth, or the complete truth so far as we know it. Now, what should we teach first? 1–2Matter is made of atoms Figure 1–1. Bill Gates Favorite Books. Park East Press Even though Gates can get a meeting with almost anyone, he can't land a sit-down with Norman Borlaug, the late biologist and humanitarian who led the "Green Revolution" — a series of innovations that kept a huge chunk of humanity from starving.

Bill Gates Favorite Books

"Although a lot of people have never heard of Borlaug, he probably saved more lives than anyone else in history," Gates says. "It's estimated that his new seed varieties saved a billion people from starvation," many of whom were in India and Pakistan. Borlaug was awarded the Nobel Peace Prize, the Presidential Medal of Freedom, and the Congressional Gold Medal for his efforts — and is one of only seven people to do so. For Gates, Borlaug is a model in getting important work done in the world. "Borlaug was one-of-a-kind," he says, "equally skilled in the laboratory, mentoring young scientists, and cajoling reluctant bureaucrats and government officials.

" Buy it here >> Mozambook - les ebooks de littérature - ebooks of literature. OpenClassrooms, Le Site du Zéro - Les cours les plus ouverts du Web. Graphisme & interactivité blog par Geoffrey Dorne. World of Mathematics. If we can divide a number A by a number B, without remainder, we say that B is a factor or divisor of A, and that A is a multiple of B.

World of Mathematics

For example, 7 is a factor of 21, 4 is a factor of 20 and 60 is a multiple of 12. When thinking about number problems, it is often useful to find all the factors of a number. To do this, we should note that factors always appear in pairs. For example, 7 × 3 = 21, so 3 and 7 are a factor pair of 21. Let us write down these factor pairs, until we meet in the middle: And these are indeed all the factors of 24. Some numbers are very special because they only have two factors: 1 and itself. A prime number is a positive integer which has no factors other than 1 and itself. 1 itself, by definition, is not a prime number. Prime numbers can’t be divided any further and thus can be thought of as the ‘atoms’ of numbers. Now 2, 3 and 7 are prime numbers and can’t be divided further. Eratosthenes of Cyrene (276 BC – 194 BC) The Sieve of Eratosthenes RSA Cryptography .


The Periodic Table of Videos - University of Nottingham. Find Your Name in the Periodic Table of the Elements. Top 10 Scientific Mnemonics. Humans Science is full of long lists of important information that can be very difficult to remember.

Top 10 Scientific Mnemonics

A mnemonic is a small phrase or word that helps us to remember these things. This is a list of 10 mnemonics to help you learn some important scientific terms. This is to be the first in a series of lists of mnemonics. 10. Remember this phrase and when you want to know the speed of light, count the letters in each word of the sentence. We guarantee certainty, clearly referring to this light mnemonic 299,792,458 m/sec 9.

Memorize these phrases to learn the first eighteen elements – when you are done, make up your own phrases for some of the others. Happy Henry Likes Beer But Could Not Obtain Four Nuts That gives us the first 10: Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon. Naughty Magpies Always Sing Perfect Songs Clawing Ants That gives us the next 8: Sodium (NA), Magnesium, Aluminum, Silicon, Phosphorous, Sulfur, Chlorine, Argon 8. 7. 6. 5. Met Dr Thip. To add up to. Sound Bottle : une bouteille qui remixe les sons aux alentours. 10 techniques de manipulation de l'opinion publique et de la société.

Le Petit Érudit. HowStuffWorks "Learn how Everything Works!".

La boite verte

Université Ouverte des Humanités: Le projet. TED: Ideas worth spreading. Net Sommaire. De la servitude moderne - le livre. Documentaires. Béhémoth. Tour de Babel. Empire romain. Belzébuth. Language Exchange Community - Practice Foreign Languages. ¤ Portail des civilisations anciennes. Does Language Influence Culture? Les expressions françaises décortiquées - Accueil. Fractale. Spheres. Spheres [ english | español | portugués ] Spherical Surface of Dialogue Spheres shaped by dialogue, a net of semantical combinations.


The richness of words consists in their relations with one another. A single pair of words placed together is enough to create narrative, reflections, theories, poetry, humour, or even the arbitrary… Spheres is a project in constant evolution. The spheres of relations, with available versions in Spanish (inauguration in March 2004), English (November 2004), and Portuguese (March 2005), are spaces of stimulation and inspiration; spaces in which a slow conversation among words can be developed, and through these words, among peoples. Technical requeriments: 1024x768 screen, flash player v6 (download here) "[...] In both scientific and everyday contexts, the same word can define different things, however they will not be radically different. +read complet text: The Words of the Sciences of Complexity: from Ambiguity to Dialogue read and write on the spheres.

CALCULATRICE SCIENTIFIQUE EN LIGNE. Share Book Recommendations With Your Friends, Join Book Clubs, Answer Trivia. Ebooks libres et gratuits. Ebooks gratuits - Télécharger des revues et magazines en pdf gratuits. Free Audio Books - Download an audio book in mp3 or iPod format today! FILMS7 VOD - VIDEOS - CLIPS - BANDES DEMOS COMEDIENNES - VIDEO A LA DEMANDE - FILMS A VOIR EN LIGNE - CINEMA D'AUTEUR. Free Audio Book - Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences by René Descartes. By: René Descartes (1596-1650) The Discourse on Method is best known as the source of the famous quotation “cogito ergo sum”, “I think, therefore I am.” ….

It is a method which gives a solid platform from which all modern natural sciences could evolve. With this work, the idea of skepticism was revived from the ancients such as Sextus Empiricus and modified to account for a truth that Descartes found to be incontrovertible. Descartes started his line of reasoning by doubting everything, so as to assess the world from a fresh perspective, clear of any preconceived notions. First Page: by Rene Descartes.

Shahi - A visual dictionary. Visual Thesaurus. Hugh Laurie - Tout est sous contrôle - Livre Audio[MU] sur megaupload dvdrip.