Baseball. Often dismissed by many because of how "slow" and "boring" it is. This being said, anybody who knows anything about physics should strongly disagree with these statements. The truth is, every 15- 20 seconds, a ball flies towards the batter travelling 80+ mph and curving up to a foot in one direction all the while a batter is trying to hit that ball to distances exceeding 400 feet. The most interesting piece of this intense chain of events is the movement of the ball, which requires years of practice, refinement and sometimes plain luck. The most common type of moving pitch is the curveball. This pitch, depending on the pitcher, can be thrown up to 90 mph and break as much as 16 inches. There are many methods to throwing the curve but the real secret lies in rpms. One of the best pitchers in baseball, Clayton Kershaw, imparts 1628 rpm of spin on his curveball, which makes it one of the best ever seen. Recently, the study of rpm has been a widely discussed topic because of the new developments in MLB's PITCHf/x system. This system, which was phased into all 30 stadiums starting in 2006, uses 2 cameras mounted in the stadium that track location, velocity, launch angle, release point and spin rate. This state of the art system proves the theory that rpms are the key to curveballs. The raised seams on a baseball make it easy to generate pressure differential, and curveballs utilize this advantage by creating an area of high pressure above the ball, forcing it down faster than gravity would normally take it. Higher rpms generate higher pressure and therefore a better pitch that moves more, has more velocity and will fool more batters.
Here are some great examples of rpms at work..