Projectile Motion: John Philoponus, a Christian philosopher, scientist, and theologian who lived in
Alexandria, Egypt, during the sixth century AD, challenged Aristotle’s idea that air could rush around
behind an arrow and push it forward. Instead, Philoponus proposed that the medium just provided a
resisting force. To explain how the projectile continued to move, he proposed that some sort of motive
force is imparted to the projectile itself so that it continues to move of its own accord. The less resistance it
encounters, the less it will be slowed. For the next few centuries, Arab scholars, such as Ibn Bajja of
Saragossa, Spain, continued to think and write about the force that keeps a projectile moving. Some
thought that the motive force would eventually die away and disappear, while others thought it would last
indefinitely unless it encountered resistance.