Explain the concept of "moment of inertia."

The moment of inertia is a fundamental concept in rotational dynamics that quantifies an object's resistance to changes in its rotational motion. This resistance is a result of the object's mass distribution relative to the axis of rotation. Essentially, the further the mass is from the axis of rotation, the greater the moment of inertia will be, leading to a higher resistance to angular acceleration.

In practical terms, if a large force is applied to an object to change its rotational speed, an object with a high moment of inertia will require more torque to achieve that change compared to an object with a low moment of inertia. This is analogous to how mass affects linear motion; just as mass contributes to an object's resistance to linear acceleration, the distribution of mass in relation to the axis of rotation influences how easily a body can be spun or rotated.

The other options do not encapsulate the proper definition of moment of inertia. For instance, the stability of the body's center of mass relates more to balance and equilibrium rather than rotational resistance. Describing speed in a particular direction pertains to kinematics rather than the rotational aspect captured by the moment of inertia. Defining gravitational pull is a matter of weight and mass, unrelated to an object’s resistance to rotational changes. Thus, the correct understanding here