L = Jω, where j is the moment of inertia and ω (ω) is the angular velocity.

In classical mechanics, angular momentum is expressed as the cross product of displacement to the origin and momentum, usually written as L, and angular momentum is a vector.

L= r×p

Where r represents the distance from the particle to the center of rotation (axis) (which can be understood as radius) and l represents angular momentum. P stands for momentum

Angular momentum: Angular momentum is a physical quantity related to the displacement and momentum of an object to the origin in physics. Angular momentum is a quantity that describes the rotating state of an object. Also known as moment of momentum. If the mass of a particle is m, the velocity is v, and its vector diameter about point O is r, then the angular momentum from point to point O of the mass is L=r×mv. Angular momentum is a vector, and its projection on the axis passing through point O is the angular momentum (scalar) of a particle on this axis. The angular momentum of a particle system or rigid body to a point (or axis) is equal to the vector (or algebraic) sum of the momentum of each particle to the point (or axis).

Direction of angular momentum: angular momentum is the cross momentum of r (the distance vector from the reference point to the particle) and the cross product of two vectors. In the right-hand coordinate system, follow the right-hand spiral method, that is, the four fingers of the right hand point in the R direction, and after turning the plane angle less than 180 degrees, the four fingers point in the momentum direction and the thumb points in the direction.