Aerodynamics is related to the flow of air around a projectile, which can influence the speed and direction of the object. For objects in water, it is called hydrodynamics.

Did you Know?

A 5000m runner uses 9% of their total energy expenditure during a race simply in overcoming air resistance. A 100m sprinter uses 20%.

The air flow around a ball thrown through the air differs greatly depending on whether it has a smooth surface or a rough surface (e.g. stitches on a baseball or cricket ball, dimples on a golf ball).

In the flight of a smooth ball, the air molecules travel around the ball to the back where they meet and mingle and combine to push the ball forward. The pressure behind the ball is less than the pressure in front.

When the ball has an uneven surface, turbulence occurs as the air flows over the ball. The turbulence causes the air to stick to the ball just a little longer and increases the wake (as in a boat's wake) which increases drag.