Final answer:
The boy's motion on the spiral slide is a combination of constant linear velocity and uniform circular motion.
Step-by-step explanation:
The motion of the boy sliding down the spiral slide can be described as a combination of circular motion and linear motion. As the boy slides down the smooth spiral slide, his z coordinate decreases by 2 m per turn of the spiral, indicating a linear motion in the downward direction.
The boy's speed is 2 m/s, which indicates a constant linear velocity. However, since the spiral slide is curved, the boy is also undergoing circular motion. This circular motion is responsible for the change in his z coordinate per turn of the slide.
Therefore, the boy's motion on the spiral slide can be described as a combination of constant linear velocity and uniform circular motion.