Reported May 2009

WHAT MAKES A GOLF BALL FLY? : The aerodynamics of a golf ball involves two pairs of opposing forces: lift and weight (the pull of gravity), and thrust and drag. Hitting a golf ball creates a forward thrust. It also creates a rapid backspin on the ball as it travels. This forces the airflow downward and produces lift. Lift occurs whenever the air pressure beneath an object, like an airplane's wing, is greater than the air pressure above it. But a golf ball can't travel in the air forever. The force of lift is countered by the equal and opposite force of drag -- the result of air friction on the ball's surface -- and the pull of gravity (since the object has weight). Eventually these forces become greater than the lift and thrust, and the golf ball descends to the ground.

DIMPLES ARE SO CUTE: The dimples on a golf ball are also important when it comes to keeping the ball in the air longer. Dimples allow air to flow over the ball's surface more easily, with less friction, and therefore less drag. Changing the pattern of dimples alters the amount of drag on the ball as it flies through the air. The researchers developed a computer algorithm that could quickly and accurately analyze the interactions that happen as the dimpled ball cuts through the air.

The American Mathematical Society, the Mathematical Association of America, and the American Physical Society contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Elias Balaras
University of Maryland
College Park, MD 20742
(301) 405-8268
balaras@umd.edu

Ivars Peterson
Mathematical Association of America,
Washington, DC 20036-1358
(800) 741-9415
http://www.maa.org
ipeterson@maa.org

Mike Breen and Annette Emerson
American Mathematical Society
Providence, RI 02904-2294
(800) 321-4267
http://www.ams.org
paoffice@ams.org

James Riordon, Media Relations
American Physical Society
College Park, MD
(301) 209-3238
http://www.aps.org
Riordon@aps.org

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