What happens to air velocity when it passes over the fins of air cooled engines?

The correct answer reflects that when air passes over the fins of air-cooled engines, its velocity slows down. This deceleration occurs due to the interaction between the air and the surface of the fins, which are designed to increase the surface area for heat dissipation. As the air is forced to flow around the fins, it experiences resistance and turbulence, which leads to a drop in speed compared to its velocity before encountering the fins.

Air-cooled engines rely on the flow of air to carry heat away from the engine components, and while the design of the fins promotes effective cooling by increasing the contact area, it also disrupts the smooth flow of air. The fins create additional surface area that the air must flow around, leading to a decrease in air velocity as it moves across the fins. This concept is essential for understanding how effectively air-cooled engines can manage thermal loads and maintain optimal operating temperatures.