Q1: The moment of inertia of a body comes into play in __________ motion.

ANS:C - rotational

The moment of inertia of a body comes into play in rotational motion. Moment of inertia, also known as rotational inertia, is a measure of an object's resistance to changes in its rotational motion. It depends on both the mass and the distribution of mass within the object relative to the axis of rotation. In rotational motion, objects rotate around an axis, and the moment of inertia determines how difficult it is to change the angular velocity of the rotating object. In contrast, linear motion refers to motion along a straight path, such as in translational motion, where the moment of inertia is not relevant. Curvilinear motion involves motion along a curved path, and while moment of inertia may indirectly affect such motion in certain contexts, it is most directly associated with rotational motion. Therefore, the correct answer is "rotational."