Angular acceleration is a vector quantity, meaning it has both magnitude and direction. Its direction is determined by the right-hand rule:

1. Curl your fingers in the direction of the rotation.

2. Your thumb will point in the direction of the angular acceleration.

Here's how it works in practice:

* Clockwise rotation: If an object is rotating clockwise, your fingers will curl clockwise, and your thumb will point into the plane of rotation.

* Counterclockwise rotation: If an object is rotating counterclockwise, your fingers will curl counterclockwise, and your thumb will point out of the plane of rotation.

Important Note: The direction of angular acceleration is not the same as the direction of the tangential velocity of a point on the rotating object. The tangential velocity is always tangent to the circular path, while the angular acceleration points along the axis of rotation.

Let me know if you'd like a visual example or have any more questions!