Motion in Two Dimensions, aka: Motion in Two Directions, aka: Parabolic Motion

When objects are projected through the air, they move in a parabolic trajectory.

There are two primary forms of projectile motion that we will study.
Objects that initially move with a zero initial angle of inclination. (such as driving a car off a cliff)
Objects that initially move with an inclination angle between zero and 90 degrees. (such as shooting a cannon into the air

for zero initial angle of inclination:
the object will initially go over and down.
acceleration vertically will be +9.81 m/s2
the initial velocity vertically is zero ( as if dropped )

acceleration horizontally will be zero
the initial and final horizontal velocities will be the same.

for angled inclination:
the object will initially go up and down.
acceleration vertically will be -9.81 m/s2
the final velocity vertically will be zero at the top of the object's path.

acceleration horizontally will be zero
the initial and final horizontal velocities will be the same.