Answer to Question #21514 in Mechanics | Relativity for AJ Robison

The horizontal component of a projectile's velocity doesn't change, until the projectile hits something or falls to the ground. The vertical component of a projectile's velocity becomes [9.8 meters per second downward] greater each second when going downwards (less each second when going upwards). At the maximum height of its trajectory, the projectile's vertical velocity is zero.