There are two things in mechanical engineering that we […]
There are two things in mechanical engineering that we call "moments of inertia". Both are important for different parts of machine part design.
One is the area moment of inertia. This one is used for beam bending equations. This is more a mathematical characterization of the bending stiffness and bending strength of the beam cross section. The MOI is used to calculate bending stiffness, deflection under load, and stress in the material.
The other is the moment of inertia mass. That represents resistance to angular acceleration. It needs more torque to get the part with higher angular acceleration if it has higher mass MOI.
These two are very important for the design of machine parts and must not be confused.