Circular motion

Circular motion is motion whose path is a circle. Examples include a rock in a sling or the tips of the hands of a clock.

In circular motion, the velocity of the object is always tangential to the circular path and perpendicular to the radius of the circular path. How do we know? In the sling example, if we fire the rock at a given point, its path will be a straight line tangential to the circle at the point of release.

Circular motion can be uniform, which means the speed remains constant over time, only the direction of the velocity changes; and non-uniform, when both the magnitude and the direction of the velocity change over time.