Final answer:
The magnitude of the velocity vector for each point on the hoop as viewed by someone moving along with the same velocity is 0 m/s because the relative velocity is zero for someone moving with the hoop.
Step-by-step explanation:
To determine the magnitude of the velocity vector as viewed by someone moving along with the same velocity as the hoop, we consider that the observer is moving with the same speed and direction as the hoop itself. For an observer sharing the same velocity, all points on the hoop would appear to be at rest relative to the observer, because their relative velocity is zero. Thus, the magnitude of the velocity that the observer measures for each point would be 0 m/s.
Regardless of the given velocities, such as 3 m/s, 5 m/s, or 7 m/s, when viewed by an observer moving with the same speed and direction, these velocities would negate due to the relative motion, resulting in an observed magnitude of zero for each point.