Anything that moves through air encounters resistance, or drag force. The spinning motion of a curveball causes the air on one side of the ball to encounter a different level of resistance than the other. At the top of the ball, the air is traveling in the same direction as the spin. On the bottom, the air travels in the opposite direction. The differing resistance causes the ball to veer downward -- called breaking -- and to the left.
Function
To throw a curveball, pitchers place a thumb on the bottom of the ball and their index and middle fingers on the stitching. As they release the ball, they add a little twist by flicking their wrist so that the ball spins roughly counterclockwise when viewed from above.
Benefits
When a curveball leaves the pitcher's hand, it appears to the batter as if it is heading to the right. This causes the batter to prepare to swing toward that area. Near the end of its path, the ball breaks down and to the left, throwing off the batter. In Major League Baseball, a good curveball can deviate 17-1/2 inches from a straight line path, according to Exploratorium.
Types
Other pitches also employ spinning action to create specific effects. A screwball happens after a pitcher adds clockwise spin -- the opposite of a curveball’s spin -- causing the ball to break down and to the right. A fastball requires backward spin, which pitchers add by rolling their fingers downward as they release the ball. This causes the ball to rise and stay in the air longer. A slider requires the reverse of a fastball’s spin. It curves downward and to the left.
Considerations
Pitching requires proper form, not only so that the ball curves in the correct way, but also to minimize the risk of injury to the pitcher's arm. For example, a slider is a dangerous pitch because it can damage the connective tissue in the forearm. For that reason, many coaches and trainers won't allow pitchers younger than 18 years of age to throw sliders.
Member Comments