Precession Of Curveballs In Sports

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Curveballs in sports are generally caused by precession. Spin on the ball introduces anglewarp. Distortion of the precession can be caused or enhanced by such things as the dimples on a golf ball, fuzz on a tennis ball, stitches on a baseball, or possibly even by certain types of wax on a bowling ball. A Ping-Pong ball is so small and light that very little distortion is needed. It curves considerably with proper paddle motion. If it were slightly larger or heaver it might need to be given a rougher surface. Notice that the delivery of motion to all of the balls mentioned above is designed to provide the required spin. Witness the ribbed face of a golf club, the tight strings of a tennis racket, the sandpaper on a Ping-Pong paddle…show more content…
The shape of the football is important to the game because it reduces the chance of an unintended curveball. It also reduces the ability to throw an intentional curveball while also making any attempt perceptible in the “wobble” of the ball. Some (vertical) precession of a passed football is desirable, however. As the football is released by the passer, the axis of the spiral needs to be slanted upward in the direction and at the precise angle the ball will initially be traveling through the air. The football, as a projectile in still air, will travel a (nearly) parabolic trajectory. As the direction of travel arcs forward, the axis of rotation (spiral), if not for precession, would lag behind. This would expose the nose of the football to upward wind pressure. For a right-handed passer, upward wind pressure would cause the nose of the ball to try to tip up. The anglewarp of rotation is traveling to the right across the top of the ball as it maintains the rotation. When the axis of rotation encounters the anglewarp across the top, it causes a slight precession to the right (as seen by the passer). For left-handed passers the precession would be similar but to the…show more content…
For example, there would be no precession were this experiment to be performed by a robot in a vacuum, or near vacuum such as in space, on the moon, or in an evacuated pressure chamber. References above to “wind” when passing the ball in still air refer to the air “passing over” the moving ball. “Blowing” wind can complicate the situation considerably. Not only can blowing wind alter the ball’s trajectory, it can also cause sidewise precession. Players should practice in windy conditions as often as practical even if the “practice” wind must be artificial. Notice also that air is not directly responsible for precession, but air is necessary for wind, and headwind can provide force and lateral (initially upward) force on the nose is necessary for precession. Precession of spinwarp is not new science, but its narrative does provide better understanding. All football coaches should know this. However, most people seem to think that greater power behind the pass combined with the resistance of the air reduces the precessional “wobble.” It is probably true, however, that greater distance is produced by less

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