Angular Kinetics - Moment of Inertia (MoI) and Angular Momentum
INERTIA is a body’s tendency to resist acceleration, and although not a measurable
quantity, it is proportional to a body’s mass.
MOMENT of INERTIA is simply inertia or resistance to ANGULAR ACCELERATION
It too is proportional to a body’s mass, but here the DISTRIBUTION OF THE BODY’S
MASS WITH RESPECT TO ITS AXIS OF ROTATION is even more important.
Swing a golf club from its grip end and from its head end. Which is easier? The latter.
WHY? The more closely a body’s mass is concentrated to its axis of rotation, the
easier it is to swing (rotate) it.
[ I=mr2 is the MoI of a single mass particle and I=mk2 for a body, with radius of
gyration, k, being the distance from the body’s axis of rotation to a point where the
body’s mass could be concentrated with respect to that axis ]