Moment of inertia is a measure of an object's resistance to changes in its rotational motion. It is similar to mass in linear motion and depends on the object's mass distribution and its distance from the axis of rotation.
The moment of inertia is calculated by multiplying the mass of each particle in an object by the square of its distance from the axis of rotation and then summing up these values for all the particles in the object.
Moment of inertia and rotational inertia are essentially the same concept, with the only difference being that moment of inertia is used to describe the rotating motion of solid objects, while rotational inertia is used for the rotating motion of point masses.
The moment of inertia directly affects an object's rotational motion, as it determines how much torque is needed to change the object's rotational speed. Objects with a larger moment of inertia will require more torque to rotate compared to objects with a smaller moment of inertia.
The concept of moment of inertia is used in many practical applications, such as designing machines and vehicles that require rotational motion, calculating the stability of structures, and understanding the behavior of objects in a spinning motion.