Standing wave Two opposing waves combine to form a standing wave. For waves of equal amplitude traveling in opposing directions, there is on average no net propagation of energy. Moving medium As an example of the first type, under certain meteorological conditions standing waves form in the atmosphere in the lee of mountain ranges. Standing waves and hydraulic jumps also form on fast flowing river rapids and tidal currents such as the Saltstraumen maelstrom. Opposing waves In practice, losses in the transmission line and other components mean that a perfect reflection and a pure standing wave are never achieved. Another example is standing waves in the open ocean formed by waves with the same wave period moving in opposite directions. Mathematical description In one dimension, two waves with the same frequency, wavelength and amplitude traveling in opposite directions will interfere and produce a standing wave or stationary wave. and where: Examples Sound waves Light
No magic show: Real-world levitation to inspire better pharmaceuticals It’s not a magic trick and it’s not sleight of hand – scientists really are using levitation to improve the drug development process, eventually yielding more effective pharmaceuticals with fewer side effects. Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have discovered a way to use sound waves to levitate individual droplets of solutions containing different pharmaceuticals. At the molecular level, pharmaceutical structures fall into one of two categories: amorphous or crystalline. “One of the biggest challenges when it comes to drug development is in reducing the amount of the drug needed to attain the therapeutic benefit, whatever it is,” said Argonne X-ray physicist Chris Benmore, who led the study. “Most drugs on the market are crystalline – they don’t get fully absorbed by the body and thus we aren’t getting the most efficient use out of them,” added Yash Vaishnav, Argonne Senior Manager for Intellectual Property Development and Commercialization.
Physicists May Have Evidence Universe Is A Computer Simulation Physicists say they may have evidence that the universe is a computer simulation. How? They made a computer simulation of the universe. And it looks sort of like us. A long-proposed thought experiment, put forward by both philosophers and popular culture, points out that any civilisation of sufficient size and intelligence would eventually create a simulation universe if such a thing were possible. And since there would therefore be many more simulations (within simulations, within simulations) than real universes, it is therefore more likely than not that our world is artificial. Now a team of researchers at the University of Bonn in Germany led by Silas Beane say they have evidence this may be true. In a paper named ‘Constraints on the Universe as a Numerical Simulation’, they point out that current simulations of the universe - which do exist, but which are extremely weak and small - naturally put limits on physical laws. But the basic impression is an intriguing one.
Speed of Sound in some common Solids Speed of sound in some common solids like aluminum, brass, concrete and ... Speed of sound in normal air is 343 m/s. In water the speed of sound is 1433 m/s. Sound velocity in some common solids are indicated in the table below: 1 m/s = 3.6 km/h = 196.85 ft/min = 3.28 ft/s = 2.237 mph Related Topics Acoustics - Room acoustics and acoustic properties - decibel A, B and C - Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation Related Documents Tag Search en: sound speed velocity solidses: sólidos velocidad de la velocidad del sonidode: Schallgeschwindigkeit Geschwindigkeitsfeststoffe Search the Engineering ToolBox About the ToolBox We appreciate any comments and tips on how to make The Engineering ToolBox a better information source. firstname.lastname@example.org if You find any faults, inaccuracies, or otherwise unacceptable information. This site use third-party cookies. Advertise in the ToolBox
page2 WHAT IS THIRD SOUND? Superfluids Speed of a Third Sound Wave Two-fluid hydrodynamics What's it good for? Sound modes in bulk liquid For more information Third sound References Superfluids Water flowing down a pipe experiences viscous drag, which causes it to lose energy and slow down. Liquid helium (both 3He and 4He) and the electrons in a superconductor, have the amazing property that they can flow without this energy loss. This superfluid behavior is extremely interesting, as much for its numerous practical applications as for the beauty of the theories which have been developed to explain it. Normal fluid near a wall, such as the substrate above, tends to move with the wall.
The Measurement That Would Reveal The Universe As A Computer Simulation One of modern physics’ most cherished ideas is quantum chromodynamics, the theory that describes the strong nuclear force, how it binds quarks and gluons into protons and neutrons, how these form nuclei that themselves interact. This is the universe at its most fundamental. So an interesting pursuit is to simulate quantum chromodynamics on a computer to see what kind of complexity arises. There are one or two challenges of course. That may not sound like much but the significant point is that the simulation is essentially indistinguishable from the real thing (at least as far as we understand it). It’s not hard to imagine that Moore’s Law-type progress will allow physicists to simulate significantly larger regions of space. Again, the behaviour of this human cell would be indistinguishable from the real thing. It’s this kind of thinking that forces physicists to consider the possibility that our entire cosmos could be running on a vastly powerful computer. First, some background.
waves - What characterizes a metallic sound, and why do metals have a metallic sound? Interestingly something sounding metallic has its origin in its dimensions rather than the material, and this effect is only amplified by the material. The character of perceived sound is mostly determined by the excited oscillations of an object, the so called modal structure. The modes of an object depend on the geometry. An approximately one-dimensional object like a long thin cylinder will have mode frequencies that come as integer multiples of a fundamental frequency. These can be easily grouped by our auditory cortex to result in a single tonal perception with a timbral character depending on the energy distribution in the vibrational modes. We call this frequency structure "harmonic". A 2 or 3 dimensional object has additional frequencies that cannot be described as harmonic overtones of a fundamental. If there is no good harmonic approximation and a lot of modes are excited with high energy then the sound is not tonal anymore.
Effet Magnus et turbulence dans le football Un article de Wikipédia, l'encyclopédie libre. L'effet Magnus et la turbulence sont deux effets aérodynamiques qui interviennent dans certaines frappes de ballon au football. On parle parfois d'« effet Carlos-Magnus-Bernoulli ». Au football, un type de frappe de balle dite « frappe enveloppée » vise à donner une trajectoire courbe au ballon. Exemple célèbre[modifier | modifier le code] Coup franc de Roberto Carlos : position des joueurs et trajectoires. Cet exemple particulièrement célèbre a été étudié et expliqué par des physiciens des fluides. Problème[modifier | modifier le code] Ce type de frappe et la trajectoire qui s'ensuit posent 2 questions : Comment expliquer la déviation du ballon par rapport au début de sa trajectoire ? Cette trajectoire peut s'expliquer par l'action simultanée de deux effets physiques : Analyse[modifier | modifier le code] Une présentation plus technique est fournie par l'article. L’effet Magnus[modifier | modifier le code]
Segelqualle An den Strand gespülte Segelquallen Die Segelqualle (Velella velella) (syn. V. lata Chamisso & Eysenhardt, 1821) ist ein zu den Hydrozoen gehörendes Nesseltier (Cnidaria). Wegen ihres Baus wird die Qualle im Deutschen auch "Segler vor dem Wind" oder "Sankt-Peters-Schifflein" genannt (Petrus: Schutzheiliger der Fischer). Merkmale[Bearbeiten] Die Meduse weist vier radiale Kanäle auf und besitzt zwei Paare sich gegenüber stehender perradialer Tentakeln, einen kurzen adaxialen Tentakel und einen langen abaxialen Tentakel. Segelqualle mit randständigen Wehrpolypen Geographische Verbreitung und Lebensweise[Bearbeiten] Segelquallen leben weltweit in tropischen und subtropischen Meeren (auch im westlichen Mittelmeer), und zwar an der Wasseroberfläche der Hochsee. Feinde[Bearbeiten] Zu den Feinden der Segelqualle gehören unter anderem die zu den Nacktkiemern gehörende pelagische Schnecke Glaucus atlanticus und die Veilchenschnecke (Janthina janthina). Fortpflanzung[Bearbeiten] Literatur[Bearbeiten]