Final answer:
The movement of a rocket traveling 300 miles east is a vector quantity because it has both magnitude (300 miles) and direction (east).
Step-by-step explanation:
The quantity describing a rocket being fired into the air and traveling 300 miles going east is indeed a vector quantity. This is because a vector is defined by both a magnitude and a direction. In this case, the magnitude is 300 miles, and the direction is east. Similar to how the displacement of an Eclipse Concept jet can be described as a vector when considering its direction, the rocket's movement can be understood in terms of vectors as well.
For example, if we scale the rocket's trip by a positive scalar, such as doubling the distance traveled, the rocket would travel 600 miles east. Here, the magnitude changes, but the direction remains the same, showing the properties inherent to vectors. Therefore, knowing the rocket's trajectory allows us to discuss its movement in vector terms, as we have both the distance (magnitude) and the orientation (direction) of the movement.