Final answer:
A particle does have a turning point in its motion, where it reverses its direction; based on the provided reference, this occurs at t = 5 seconds for a certain particle's trajectory.
Step-by-step explanation:
This seeks to determine whether a particle has a turning point and if so, at what time this occurs. From the provided references, we gather that a particle does have a turning point in its motion, a moment when the velocity of the particle becomes zero and it reverses direction. Specifically, Figure 4.9 indicates that for a particle starting at the origin, there's a turning point at t = 5 seconds at an x coordinate of 25 meters, where the direction of the particle's motion in the x-axis reverses. This turning point is characterized by a change in the sign of the particle's velocity component in the x-direction.