Two children, Jason and Betsy, ride on the same merry-go-round. Jason is a distance R from the axis of rotation; Betsy is a distance 2R from the axis.

(a) Is the rotational period of Jason greater than, less than, or equal to the rotational period of Betsy?

(b) Choose the best explanation from among the following:

I. The period is greater for Jason because he moves more slowly than Betsy.

II. The period is greater for Betsy since she must go around a circle with a larger circumference.

III. It takes the same amount of time for the merry-go-round to complete a revolution for all points on the merry-go-round.