'Football season is finally upon us,and with that, team pride, or tailgating,and the perfect spiral. But how exactly does that spiral work? A good spiral throw makes 600 turns per minute—just as hasty as a cd in a cd player. As the ball spins across the field, gravity pulls the nose of the ball downwards, and the direction the football changes slightly depending on which hand you employ to throw it. Watch materials scientist Ainissa Ramirez explain the physics behind the perfect landing pass.' -- +TIME
Source: blogspot.com