What physical characteristic does the moment of inertia of a rotating object most directly and accurately measure?

Explanation:

Moment of inertia is defined as  resistance offered by the rotating body to the acceleration or deceleration and it is calculated by the multiplying the mass of the object into square of the perpendicular distance from its axis of rotation.

Moments of inertia of the rotating object is a sum of moments of inertia of each particle in the body into the square of distance from its axis of rotation..

r = perpendicular distance from the axis of the rotation

From the definition it evident that Moment of inertia is directly proportional to the mass of the object.

An individual can easily determine the mass of the rotating object with help of moment of inertia and perpendicular distance from the axis of rotation.

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".