FAA Ground School Practice Test

According to Bernoulli's principle, what happens to air traveling faster over the top surface of an airfoil?

1. It creates higher pressure

2. It slows down

3. It causes lower pressure above the airfoil

4. It remains constant

The correct answer is: It causes lower pressure above the airfoil

According to Bernoulli's principle, as the speed of a fluid (in this case, air) increases, its pressure decreases. When air travels faster over the top surface of an airfoil, this increased velocity results in a decrease in pressure above the airfoil. This phenomenon is crucial in creating lift, as the higher pressure below the airfoil compared to the lower pressure above generates the necessary upward force to keep an aircraft in flight. The relationship between airspeed and pressure is fundamental in understanding how airfoils operate, making the decrease in pressure above the airfoil an essential element of aerodynamic lift. This principle is not only pivotal for pilots and engineers but also helps in the design of airfoils to maximize efficiency and performance.