By Tiffani Kolozian, STEM co-teacher
We used no-dimple golf balls like this one in our experiment.
Last week at Dunwoodie Golf Course, we compared the flight of completely smooth golf balls to normal balls with dimples.
For our experiment, the students noted that the independent variable was the type of ball — with dimples or without. (The no-dimple balls were supplied by the USGA, which uses them at its Research and Test Center in Far Hills, NJ.) The students also decided that their dependent variable would be carry, or how far the ball flew. Our controls were clubhead speed, the club we used, wind speed, and the mat the ball was hit from.
Of course these controls were not exact as the the wind was always changing, and Teaching Professional Brian Hwang, as good as he is, cannot hit every shot exactly the same. But the conditions and his swing were consistent enough to show that the type of golf ball made a huge difference.
After watching Brian hit a series of 8-iron shots with both types of ball, our students easily concluded that a golf ball without dimples did not go nearly as far as a ball with dimples, and flew with a different trajectory.
After our experiment, we talked about how dimples work and learned that they affect two crucial aspects of aerodynamics — drag and lift. First, dimples allow air to flow more smoothly around a ball’s surface, which decreases the wake and low-pressure area behind the ball, resulting in less drag. Second, the dimples increase lift by causing the air to move faster at the top of the ball, creating lower pressure there. The higher pressure below the ball lifts it.
Below is a great video explanation of how dimples work from the USGA and NBC: