Baseball has been America's national pastime since the mid-1850s, but the science behind baseball is still being studied today.
Technology such as high-speed cameras and wind tunnels has allowed us to study different pitches to understand what makes them change direction, or break, on their way to home plate. What have we learned?
A combination of air pressure, spin, and the seams on the ball give each pitch special characteristics. Let's take a look at how these work in one famous pitch -- the curveball.
A curveball is hard to hit because the ball drops up to 18 inches as it approaches home plate. The main reason for this is the spin of the ball. Air moves around the ball when it is thrown which creates friction, also known as drag. A smooth ball that is not spinning has the same amount of drag on the top and bottom. A spinning ball lets the air move around it at different speeds. The part of the ball spinning in the same direction as the air flow has less drag; the opposite side of the ball experiences more drag.
A curveball is thrown with topspin. In topspin the bottom of the ball is moving away from the batter and the top is spinning toward the batter. This topspin causes more drag and more air pressure at the top of the ball than at the bottom. A force called the Magnus force pushes the ball in the direction of lowest air pressure. In the case of the curveball, the pressure is lowest at the bottom of the ball. That is why a curveball breaks downward. The seams greatly influence the drag of the ball; expert pitchers use them to increase the effect of the Magnus force. The next time you see a strikeout at PNC Park, you'll know how the pitcher made it look so easy.