a) Object C (the disk) has the greatest rotational inertia (
)
b) Object B (the sphere) has the smallest rotational inertia (
)
Explanation:
The moments of inertia of the three objects are the following:
1) For a hoop of negligible thickness, it is

where M is its mass and R its radius. For the hoop in this problem,
M = m
R = r
Therefore, its moment of inertia is

2) For a solid sphere, the moment of inertia is

where M is its mass and R its radius. For the sphere in this problem,
M = 2m
R = r
Therefore, its moment of inertia is

3) For a disk of negligible thickness, the moment of inertia is

where M is its mass and R its radius. For the disk in this problem,
M = 3m
R = r
Therefore, its moment of inertia is

So now we can answer the two questions:
a) Object C (the disk) has the greatest rotational inertia (
)
b) Object B (the sphere) has the smallest rotational inertia (
)
Learn more about inertia:
brainly.com/question/2286502
brainly.com/question/691705
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