The Angular frequency reference article from the English Wikipedia on 24-Apr-2004
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Angular frequency

In physics (specifically mechanics), angular frequency ω (sometimes called angular velocity) is a measure of rotation rate, almost invariably given in units of radians per second, or simply s−1 since radians are dimensionless. One revolution is equal to 2π radians, hence

where T is the period and f is the frequency.

Using angular frequency instead of ordinary frequency is convenient in many applications, as it avoids the excessive appearance of π. In fact, it is used in many fields of physics involving periodic phenomena, such as quantum mechanics and electrodynamics.

For example:

Using 'ordinary' frequency, this equation would be:

Note also that

and therefore that

Where T is the period and v is the velocity.