“Vomit Comet” is a nickname for any airplane that briefly provides passengers with a nearly weightless environment by following a parabolic vertical flight path. The aircraft mimics the trajectory of an object in free-fall and therefore does not exert any g-force on its contents. As a result, passengers have zero apparent weight relative to the aircraft. According to the director of the Reduced Gravity Research Program, what percentage of passengers on zero-g flights becomes violently ill? Discuss