9781422274811

The Magnus Effect Can a player do anything to reduce the forces on the ball? Soccer players know this trick—kicking the ball off center. When a ball is kicked off center, the ball will begin to spin, and the direction as well as the speed of the spin determines how much the ball will curve as it flies through the air. It is the same principle that occurs in baseball when the pitcher throws a curve ball. This effect is known as the Magnus effect. German physicist Gustav Magnus first described the spinning effect in 1852 when he was trying to determine why spinning bullets deflected to one side or the other. What are the physics behind the Magnus effect? The off-center kick initiates the spin, and as the ball goes through the air, the drag (friction between the ball and the air) causes the air to react to the spin direction. The ball is moving forward at the same time it is spinning, and the spin makes the air flow faster on one side of the ball. Let’s say the soccer player kicks the ball to the right of the center; this will cause the ball to spin counterclockwise.

Players try to use the Magnus effect to their advantage when taking free kicks.

CHAPTER 1 : FORCES THAT ACT ON A SOCCER BALL

11