Objects in motion can have a path that lies on a plane. This kind of motion is called two-dimensional motion. Familiar examples of two-dimensional motion are the flight of a batted baseball, a bullet fired from a gun, a javelin thrown into the air, an athlete taking a long jump, and an object thrown up in the air. 

The baseball, the bullet, the javelin, the athlete, and any object thrown up in the air are called projectiles. In this type of motion, the projectile moves in horizontal and vertical paths simultaneously. The horizontal and vertical components of the motion, however, must be regarded independently. The path the projectile travels, called its trajectory, is an inverted parabola. *(for the horizontal formula~ picture attached)