Therefore, the total angular momentum of the solid with
respect to point
is
where
correspond to the linear momentum of the center of mass,
.
Then, the total angular momentum of the solid is
The previous expression presents the total angular
momentum of a solid object with respect to an arbitrary point
. If
,
the rotational angular momentum is the same independent of the selected
point for calculating the angular momentum. Thus, the rotational angular
momentum of a solid, when turning on an axis going through its center of
mass, is an intrinsic property of the object. It is called the **spin
angular momentum**. On the other hand, if
,
the added term to the total angular momentum can be called the "orbital"
angular momentum. |