This document defines key concepts related to motion including motion, reference point, frame of reference, speed, force, balanced forces, and unbalanced forces. Motion is defined as an object changing position over time compared to a reference point. Speed is the distance an object travels due to force over time. Balanced forces are equal and opposite forces resulting in no net force and no change in motion, while unbalanced forces are unequal forces resulting in a net force and change in speed or direction.