What describes a projectile's vertical motion?

A projectile's vertical motion is characterized by constant acceleration due to gravity. This acceleration is approximately 9.81 m/s² downward near the Earth's surface. When an object is projected into the air, it experiences the force of gravity pulling it downwards throughout its flight. This means that as the projectile rises, it slows down until it reaches its maximum height, and then it accelerates downward as it falls back to the ground.

Constant acceleration due to gravity is significant because it leads to well-defined equations of motion, which can be used to predict various characteristics of the projectile's path, such as the time it takes to reach maximum height or how far it will travel horizontally before hitting the ground.

While it may seem intuitive to think of vertical motion as exhibiting constant velocity, this is not the case when gravity is acting on the projectile. Instead, the projectile's vertical velocity changes continuously as it rises and falls. An idea of zero acceleration applies in scenarios where no forces act on an object, but in the case of a projectile, gravity is an ever-present force influencing its motion. Thus, the description of vertical motion as having uniform acceleration due to the constant force of gravity is indeed the most accurate representation of what occurs in projectile motion.