of: a particle
about: a chosen origin O, from which the position of the particle is specified by the position vector
is: 
where 
is the momentum of the particle. [P2.8]
is also known as: the moment of momentum of the particle about O. [M2.7]
of: a collection of particles
about: a given point P
is: the (vector) sum of all the moments of momenta of each of the particles about P. [P2.8, P11.3]
of: a rigid body
with: angular velocity 
about a single fixed axis of rotation, and moment of inertia 
about that axis
is given by: 
[P2.8]
has as its SI unit: 
(i.e. kilogram metre squared per second).
See conservation of angular momentum.
Copyright 1997, The Open University