Omega (idea)

In physics, the Greek letter omega is used to denote several things. The lowercase omega is generally used to denote angular quantities, specifically:

• angular frequency, which is a useful frequency measurement for many oscillating systems (because it can be used inside a trig function). It is equal to the 'ordinary' frequency multiplied by 2\pi.
• angular velocity. This is actually interchangeable with angular frequency in uniform circular motion (they're both measurements in radians/second), but is generally used in a completely different context. The context that angular velocity is used most often in is rotational dynamics, where the angular velocity is the time derivative of a position angle.

Capital omega is much less frequently utilised, being uncommon as a symbol for a quantity. The most common use of capital omega is as the symbol for the SI unit of resistance, the ohm.

Also, being the twenty-fourth letter in the Greek alphabet, stellar astronomers use it (along with the genitive of the constellation) to indicate the 24-th brightest star in a constellation. Thus we get Omega Centauri, Omega Orionis, Omega Cygni, etc, etc...