Particle acceleration


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 of time. 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{a} = {dmathbf{v}over dt}

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{ar{a = {mathbf{v} - mathbf{u} over t}

where :mathbf{ar{a is the average acceleration (m/s²)

mathbf{u} is the initial velocity (m/s)

mathbf{v} is the final velocity (m/s)

t is the time interval (s)

Transverse acceleration (perpendicular to velocity) causes change in direction. If it is constant in magnitude and changing in direction with the velocity, we get a circular motion. For this centripetal acceleration we have: mathbf{a} = - frac{v^2}{r} frac{mathbf{r{r} = - omega^2 mathbf{r}

One common unit of acceleration is "g-force", one "g" being the acceleration caused by the gravity of Earth.

In classical mechanics, acceleration a is related to force F and mass m (assumed to be constant) by way of Newton's second law: :F = m cdot a

Equations in terms of other measurements

The Particle acceleration of the air particles "a" in m/s² of a plain sound wave is::a = xi cdot omega^2 = v cdot omega = frac{p cdot omega}{Z} = omega sqrt frac{J}{Z} = omega sqrt frac{E}{ ho} = omega sqrt frac{P_{ak{Z cdot A}

ee also

* Sound pressure
* Particle displacement
* Particle velocity

External links

* [http://www.sengpielaudio.com/RelationshipsOfAcousticQuantities.pdf Relationships of acoustic quantities associated with a plane progressive acoustic sound wave - pdf]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • instantaneous sound particle acceleration — akimirkinis garsinis dalelių pagreitis statusas T sritis Standartizacija ir metrologija apibrėžtis Dydis, lygus akimirkinio garsinio terpės dalelių greičio pokyčiui per vienetinį laiko tarpą, t. y. a = δu/δt; čia δu – dalelių greičio pokytis, δt… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • Particle velocity — is the velocity v of a particle (real or imagined) in a medium as it transmits a wave. 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… …   Wikipedia

  • particle accelerator — accelerator (def. 7). [1945 50] * * * Device that accelerates a beam of fast moving, electrically charged atoms (ions) or subatomic particles. Accelerators are used to study the structure of atomic nuclei (see atom) and the nature of subatomic… …   Universalium

  • Particle accelerator — Atom smasher redirects here. For other uses, see Atom smasher (disambiguation). A 1960s single stage 2 MeV linear Van de Graaff accelerator, here opened for maintenance A particle accelerator[1] is a device that uses electromagnetic fields to… …   Wikipedia

  • Acceleration — Accelerate redirects here. For other uses, see Accelerate (disambiguation). Classical mechanics Newton s Second Law …   Wikipedia

  • Particle beam weapon — A particle beam weapon uses an ultra high energy beam of atoms or electrons (i.e., a particle beam) to damage a material target by hitting it, and thus disrupting its atomic and molecular structure. A particle beam weapon is a type of directed… …   Wikipedia

  • Particle-in-cell — The Particle in Cell (PIC) method refers to a technique used to solve a certain class of partial differential equations. In this method, individual particles (or fluid elements) in a Lagrangian frame are tracked in continuous phase space, whereas …   Wikipedia

  • acceleration — 1. The act of accelerating. 2. The rate of increase in velocity per unit of time; commonly expressed in g units; also expressed in centimeters or feet per second squared. 3. The rate of increasing deviation from a rectilinear course. See radial a …   Medical dictionary

  • Plasma acceleration — is a technique for accelerating charged particles, such as electrons, positrons and ions, using an electric field associated with an electron plasma wave. The wave is created by the passage of a very brief laser or electron pulse through the… …   Wikipedia

  • Multiphase particle-in-cell method — The multiphase particle in cell method (MP PIC) is a numerical method for modeling particle fluid and particle particle interactions in a computational fluid dynamics (CFD) calculation. The MP PIC method achieves greater stability than its… …   Wikipedia