Question

In the moment of inertia of a rod, almost all examples assume that its mass is negligible. What happens if its mass is not negligible?

Answer 1

Who said the mass is negligible? The moment of inertia can be calculated as the line integral of (r^2*dm ) .The mass is never negligible. Usually it is expressed in some other form, like for a rod the differential mass (dm) is expressed as (lambda*dx)