Final answer:
A decrease in rotation time while imaging an infant indicates an increase in the angular velocity of the imaging device, tied to concepts within kinematics of rotational motion, particularly when considering the system's angular acceleration and total moment of inertia.
Step-by-step explanation:
A decrease in rotation time while imaging an infant to prevent motion artifact refers to a change in angular velocity. In the context of kinematics of rotational motion, which describes the relationships among rotation angle, angular velocity, angular acceleration, and time, a decrease in rotation time means that the imaging device completes its rotation more quickly. This involves an increase in the angular velocity, which is the difference between final and initial values of angular velocity. Mechanically, this would likely require greater angular acceleration at the onset to achieve the faster rotation speed. Significantly, if we consider the example of a merry-go-round, angular acceleration is influenced by the rotational inertia of the system. When a child is on a merry-go-round, as opposed to when the merry-go-round is empty, the total moment of inertia is higher, resulting in a lower angular acceleration for a given force applied.