1. Projectiles
A projectile is any object that, once projected, continues in motion by its own inertia and is influenced only by the downward force of gravity.

2. Components of Projectile motion
Projectiles have a horizontal (x) component, or forward motion, as well as a vertical (y) component as the force of gravity causes it to fall.
These two components create the parabolic path of the projectile.
Projectiles can be launched horizontally or at some angle

3. Gravity’s effect on a Projectile

5. A downward moving cannonball which is gaining speed is said to have a downward acceleration. In the animation, the downward acceleration is depicted by a change in the vertical component of velocity.
This downward acceleration is caused by a downward force of gravity which acts upon the ball. (The Physics Classroom.com)