**Projectile motion** is when an object is being launched out of a cannon,
off a spring, or any other mechanism that can throw objects. Even your little sibling who
can barely pick up a rock and throw it 3 inches can be considered a mechanism throwing a
projectile (in that case, the rock).

There are several different equations that can be used in conjunction with projectiles. It is possible to find out how far the projectile has traveled (the Range equation), as well as the maximum height and how long the projectile is in the air (time of flight). Using these same equations, we will figure out how far the dice flew in the air above the Craps table, how high they went, and how long they were in the air. In dealing with projectile motion, we have to break down its movement into horizontal and vertical vectors. For the sake of simplicity, we will refer the horizontal distance as if it was the X axis on a coordinate plane, and the vertical distance as if it was the Y axis on a coordinate plane.

Many times you will see variables that you might not recognize, such as *vo*, *x*, *xo*, *g*, *a*, *t*, *y*, and *yo*. *vo* refers to the **initial velocity** of the projectile. *x* is the **final distance** or **displacement** traveled on the X axis (x is used in one of the kinematics equations that we will use later), while *xo* is the **starting point** of the projectile. *y* and *yo* are the equivalent variables on the Y axis.The time for the system to complete is expressed as *t*. The acceleration, *a*, due to gravity in expressed as the constant *g* (which is 9.80 m/s²).