Final answer:
For a rigid body not pivoted or fixed, the motion is pure translation or a mix of translation and rotation. When pivoted, the motion is strictly rotational. The fill-in-the-blank answers are A: translation, B: rotational.
Step-by-step explanation:
The motion of a rigid body which is not pivoted or fixed in some way is either a pure translation or a combination of translation and rotation. This is because when a body is free to move without a fixed pivot, it can either move in a straight line (translational motion) or can rotate about its center of mass while also translating, like a rotating hockey puck sliding over ice. The motion of a rigid body which is pivoted or fixed in some way is rotational motion. For instance, a merry-go-round is fixed at its center and all points on it follow circular paths centered on that pivot point.
In answering the student's fill-in-the-blank question: The motion of a rigid body which is not pivoted or fixed in some way is either a pure translation (A) or a combination of translation and rotation. The motion of a rigid body which is pivoted or fixed in some way is rotational (B). Therefore, the correct choices are A: translation and B: rotational.