Question

which is an example of projectile motion?
a person throwing a rock
a child swinging on a swing set
an athlete running on a track
a teacher picking up a pencil

Explanation:

Projectile motion is the motion of an object thrown or projected into the air, subject to only the acceleration of gravity. When a person throws a rock, the rock follows a curved - path under the influence of gravity. A child swinging on a swing set is a pendulum - like motion, an athlete running on a track is linear motion, and a teacher picking up a pencil is a simple hand - movement not related to projectile motion.

Answer:

a person throwing a rock