The rotational inertia of an object or system of objects refers to the general resistance the object has to a change in its rotational state. The amount of rotational inertia an object possesses depends on how much mass it has and how that mass is distributed relative to the axis of rotation.

 

The amount of mass present in a rotational system will affect the rotational inertia of that system. Both of these  systems have the same mass. But the manner in which the mass is distributed within the system is different for the two situations. And the distribution of mass is equally important in determining the rotational inertia of the system. The further the mass is distributed from the axis of rotation, the greater that the rotational inertia will be. So inspect the two systems and determine in which case is the mass furthest from the rotational axis (dashed line).