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A much smaller ball for a different sport is designed in the same way. Golf balls have a dimpled surface because the dimpling actually increases the air resistance to make a much more pronounced spinning effect. A dimpled soccer ball has the same principle. One thing that golf balls and soccer balls have in common is that in both cases, contact with the ball, whether from a golf club or a soccer player’s foot, is very, very brief. However, that contact establishes several important factors, including velocity, spin rate, and launch angle. After the kick, gravity and aerodynamics control the ball, and that is why the design of the surface of the soccer ball is so important. If a soccer ball were

smooth, it would travel only about half as far as a soccer ball with the hexagonal surface (some golf balls are made with the same hexagonal dimples as a soccer ball). Any object traveling through the air has drag and lift forces exerted on it. Drag is a force that directly opposes motion, whereas lift is a force that

The raised hexagonal pattern on a soccer ball helps it counter the force of drag as it travels through the air.

acts perpendicular to the motion of the ball. In a soccer ball, lift is directed upward. As the ball rotates in the air, the amount and direction of lift and drag vary. The indentations in the soccer ball create a thin layer of air (called a boundary layer) that clings to the surface of the ball and decreases drag. As a soccer ball spins, the air pressure on the bottom of the ball is higher than on the top, and, therefore, the ball lifts in the air.

16 CONNECTING STEM AND SPORTS | SOCCER