# Motion in a Circle

Seng Kwang
H2 Physics
Free
• 6 lessons
• 1 quizzes
• 10 week duration
• ##### Angular displacement and velocity

Learn how to describe circular motion quantitatively. The kinematics of circular motion.

• ##### Centripetal force

Learn what causes circular motion. The dynamics of circular motion.

## Direction of Angular Velocity

Using the Right-Hand Grip rule, you can identify the direction of the angular velocity vector, which lies perpendicular to the plane containing the linear velocity vector. To use the Right-Hand Grip rule, curl the fingers on your right hand such that they follow the curvature and direction of the object’s path. Your right thumb will then naturally point in the direction of the angular velocity vector. You may use the 3-dimensional animation to observe the vector changes.

## Summary:

1. $v = r\omega$, where $v$ is the linear velocity of the object, $r$ is the radius of the circular path and $\omega$ is the angular velocity.
2. For uniform circular motion, $\omega = \dfrac{2\pi}{T}$, where $T$ is the period of the circular motion or time taken to make on complete round.
3. Alternatively, $\omega = 2\pi f$ where $f$ is the frequency of rotation, or the number of complete rotations per second.