Angular Displacement 
The Ferris wheel is a circular object that turns around about an axis through a center. If a rider is sitting on the Ferris wheel and it starts to rotate in the counterclockwise direction about its center, that rider moves through an angle relative to his/her starting position. This is known as angular displacement, or an angle of rotation.
Suppose you want to determine the angular displacement, in radians, of 5.6 revolutions.
You know that each revolution (cycle) around a circle is equal to 
radians. If you go through 5.6 revolutions then:
radians, or 35.2 radians, when rounded to the nearest tenth. This is the angular displacement of 5.6 revolutions.