Consider an object moving from A to B along the circular arc in 1 second.
You can describe its speed as 3.0 cm s-1. This called the linear velocity v. Or you can describe it as 45° per second, or π/4 rad s-1. This is called the angular velocity ω (the Greek symbol omega, not the english alphabet double-u). Got it? v is distance per unit time whereas ω is angular displacement per unit time.
Starting from , we can obtain the formula the relationship between v and ω.
If the circular motion is repetitive then it has a period T. Remember that one revolution corresponds to an angular displacement of 2π rad. So we have another useful identity