Angular momentum is the moment of linear momentum of a body with respect to an axis of rotation.
Angular momentum of a particle about O is defined as
Where P is the linear momentum and r is the position vector of the particle from the given point O. The angular momentum of a system of particles is the vector sum of the angular momenta of the particles of the system. So,
Let a particle P of mass m moves at velocity v. Its angular momentum about a point O can be written as
Where is the perpendicular distance of the line of motion from O.