What are the properties of a projectile that make its path predictable? What factors might significantly change this path? How can we be sure that the "human cannonball" hits the safe target? When Commander David Scott landed on the moon he performed a famous experiment where he simultaneously dropped a hammer and a feather at the same time. Some viewers were surprised when they hit the ground at the same time. A good simulator can be a quick and useful tool for examining how a projectile behaves as it flies through the air. What are the properties of a good, predictable projectile