Projectiles
This week in Physics, we learned about projectiles.  Any object upon which the only force is gravity is considered a projectile.  Projectiles may be represented by a parabolic graph because they have a constant speed on the x-axis, but a changing speed in the y-axis (fast-slow-stop-slow-fast).  In a projectile, the x-axis usually remains at a constant velocity while the y-axis velocity slows down then increases again because of gravity's affect.  This is known as 2-D kinematics.

The picture below features a construction-worker having re-living his childhood memories or perhaps blowing off some steam from a frustrating day of work at the Hawaii Kai skatepark.  He is not considered a projectile yet because his wheels are still on the ground.  But, as soon as he airs the bowl, he will become a projectile and move on the x-axis with a constant speed, and the only force affecting him will be gravity.