A flywheel's diameter is twice that of another of the same shape and mass.The larger flywheel's rotational inertia is
A)four times the other's.
B)two times the other's.
C)the same as the other's.
D)half the other's.

Question

Quizplus · Accepted Answer

The rotational inertia of a flywheel is directly proportional to the square of its radius. Since the larger flywheel has a diameter (and hence radius) twice that of the smaller flywheel, its rotational inertia will be (2)^2 = 4 times that of the smaller flywheel.

A Flywheel's Diameter Is Twice That of Another of the Same