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
where
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:
where
formula_4 is the initial velocity (m/s)
formula_5 is the final velocity (m/s)
formula_6 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
One common unit of acceleration is "g-force", one "g" being the acceleration caused by the gravity of Earth.
In classical mechanics, acceleration formula_8 is related to force formula_9 and mass formula_10 (assumed to be constant) by way of Newton's second law:
Equations in terms of other measurements.
The Particle acceleration of the air particles "a" in m/s2 of a plain sound wave is: