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Sound Particle
In the context of particle displacement and velocity, a sound particle is an imaginary infinitesimal volume of a medium that shares the movement of the medium in response to the presence of sound at a specified point or in a specified region. Sound particles are not molecules in the physical or chemical sense; they do not have defined physical or chemical properties or the temperature-dependent kinetic behavior of ordinary molecules. Sound particles are, then, indefinitely small (small compared to the wavelength of sound) so that their movement truly represents the movement of the medium in their locality. They exist in the mind’s eye to enable this movement to be visualized and described quantitatively. Assuming the medium as a whole to be at rest, sound particles are imagined to vibrate about fixed points. See also *Sound *Particle displacement *Particle velocity *Particle acceleration In a compressible sound transmission medium - mainly air - air particles get an acce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phonon
In physics, a phonon is a collective excitation in a periodic, Elasticity (physics), elastic arrangement of atoms or molecules in condensed matter physics, condensed matter, specifically in solids and some liquids. A type of quasiparticle, a phonon is an excited state in the quantum mechanical Quantization (physics), quantization of the mode of vibration, modes of vibrations for elastic structures of interacting particles. Phonons can be thought of as quantized sound waves, similar to photons as quantized light waves. The study of phonons is an important part of condensed matter physics. They play a major role in many of the physical properties of condensed matter systems, such as thermal conductivity and electrical conductivity, as well as in models of neutron scattering and related effects. The concept of phonons was introduced in 1932 by Soviet Union, Soviet physicist Igor Tamm. The name ''phonon'' comes from the Ancient Greek language, Greek word (), which translates to ''so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Displacement
Particle displacement or displacement amplitude is a measurement of distance of the movement of a sound particle from its equilibrium position in a medium as it transmits a sound wave. The SI unit of particle displacement is the metre (m). In most cases this is a longitudinal wave of pressure (such as sound), but it can also be a transverse wave, such as the vibration of a taut string. In the case of a sound wave travelling through air, the particle displacement is evident in the oscillations of air molecules with, and against, the direction in which the sound wave is travelling. A particle of the medium undergoes displacement according to the particle velocity of the sound wave traveling through the medium, while the sound wave itself moves at the speed of sound, equal to in air at . Mathematical definition Particle displacement, denoted δ, is given by :\mathbf \delta = \int_ \mathbf v\, \mathrmt where v is the particle velocity. Progressive sine waves The particle displ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Velocity
Particle velocity is the velocity of a particle (real or imagined) in a medium as it transmits a wave. The SI unit of particle velocity is the metre per second (m/s). In many cases this is a longitudinal wave of pressure as with sound, but it can also be a transverse wave as with the vibration of a taut string. When applied to a sound wave through a medium of a fluid like air, particle velocity would be the physical speed of a parcel of fluid as it moves back and forth in the direction the sound wave is travelling as it passes. Particle velocity should not be confused with the speed of the wave as it passes through the medium, i.e. in the case of a sound wave, particle velocity is not the same as the speed of sound. The wave moves relatively fast, while the particles oscillate around their original position with a relatively small particle velocity. Particle velocity should also not be confused with the velocity of individual molecules, which depends mostly on the temperature an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges. Acoustics Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an ''acoustician'', while someone working in the field of acoustica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Displacement
Particle displacement or displacement amplitude is a measurement of distance of the movement of a sound particle from its equilibrium position in a medium as it transmits a sound wave. The SI unit of particle displacement is the metre (m). In most cases this is a longitudinal wave of pressure (such as sound), but it can also be a transverse wave, such as the vibration of a taut string. In the case of a sound wave travelling through air, the particle displacement is evident in the oscillations of air molecules with, and against, the direction in which the sound wave is travelling. A particle of the medium undergoes displacement according to the particle velocity of the sound wave traveling through the medium, while the sound wave itself moves at the speed of sound, equal to in air at . Mathematical definition Particle displacement, denoted δ, is given by :\mathbf \delta = \int_ \mathbf v\, \mathrmt where v is the particle velocity. Progressive sine waves The particle displ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Velocity
Particle velocity is the velocity of a particle (real or imagined) in a medium as it transmits a wave. The SI unit of particle velocity is the metre per second (m/s). In many cases this is a longitudinal wave of pressure as with sound, but it can also be a transverse wave as with the vibration of a taut string. When applied to a sound wave through a medium of a fluid like air, particle velocity would be the physical speed of a parcel of fluid as it moves back and forth in the direction the sound wave is travelling as it passes. Particle velocity should not be confused with the speed of the wave as it passes through the medium, i.e. in the case of a sound wave, particle velocity is not the same as the speed of sound. The wave moves relatively fast, while the particles oscillate around their original position with a relatively small particle velocity. Particle velocity should also not be confused with the velocity of individual molecules, which depends mostly on the temperature an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Acceleration
In a compressible sound transmission medium - mainly air - air particles get an accelerated motion: the particle acceleration or sound acceleration with the symbol a in metre/second2. In acoustics or physics, acceleration (symbol: ''a'') is defined as the rate of change (or time derivative) of velocity. It is thus a vector quantity with dimension length/time2. In SI units, this is m/s2. To accelerate an object (air particle) is to change its velocity over a period. Acceleration is defined technically as "the rate of change of velocity of an object with respect to time" and is given by the equation \mathbf = \frac where *''a'' is the acceleration vector *''v'' is the velocity vector expressed in m/s *''t'' is time expressed in seconds. This equation gives ''a'' the units of m/(s·s), or m/s2 (read as "metres per second per second", or "metres per second squared"). An alternative equation is: \mathbf = \frac where *\mathbf is the average acceleration (m/s2) *\mathbf is the init ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
