1. The Physics of Baseball
From the book by the physicist and baseball fan Robert Adair.
A smooth ball surprisingly
experiences more friction than a rough ball, or a baseball with stitches (for velocities of mph). Smooth airflow creates a layer of air that moves with the ball and thereby magnifies its size. Turbu-lent flow does not show this layer. For velocities above 150 mph the smooth ball also loses its air layer. Now the friction becomes lower than that of the rough ball, as expected.
The forces of gravity and friction (= drag)
become equal for a 95 miles/hour fastball.

2. Dimples Make a Golf Ball Fly Faster
Smooth golf ball:
More displaced air, more resistance.
Dimpled ball:
Less displaced air, less resistance.
Wire loop simulating dimples (roughness)

3. Smooth vs. Turbulent Water Flow
Sharkskin:
A structured surface reduces drag.