If all of the objects illustrated in the figure have equal masses, the moment of inertia about the indicated axis is largest for the
A) ring.
B) cross.
C) sphere.
D) cube.
E) rod.

Question

If all of the objects illustrated in the figure have equal masses, the moment of inertia about the indicated axis is largest for the
A) ring. 
B) cross. 
C) sphere. 
D) cube. 
E) rod.

Quizplus · Accepted Answer

The moment of inertia depends on the distribution of mass relative to the axis of rotation, and the ring has all of its mass distributed farthest away from the axis of rotation. This means it will have the largest moment of inertia of all the objects with equal mass. The other objects have their mass distributed either closer to the axis of rotation, or in a more spread out manner that doesn't contribute as much to the moment of inertia.

If All of the Objects Illustrated in the Figure Have