Private Pilot Private Exam

Which statement relates to Bernoulli's principle?

1. Faster air over the wing results in higher pressure on the upper surface.

2. Air traveling faster over the upper surface of an airfoil causes lower pressure on that surface.

3. Weight is irrelevant to lift generation according to Bernoulli's principle.

4. Drag is proportional to the square of the speed of the aircraft.

The correct answer is: Air traveling faster over the upper surface of an airfoil causes lower pressure on that surface.

Bernoulli's principle explains the behavior of fluids in motion and is crucial in understanding how lift is generated on an airfoil. When air moves over the curved upper surface of a wing, it travels faster than the air moving beneath the flatter bottom surface. According to Bernoulli's principle, as the speed of fluid increases, its pressure decreases. Therefore, the faster airflow over the upper surface creates a lower pressure compared to the higher pressure on the lower surface of the wing. This pressure difference results in an upward lift force, allowing the aircraft to rise. The other options do not accurately reflect Bernoulli's principle. For instance, stating that faster air results in higher pressure contradicts the principle itself. The notion that weight is irrelevant to lift generation does not align with the comprehensive understanding of flight dynamics, which includes the balance between lift and weight. Additionally, while drag can be influenced by speed, the specific proportionality to the square of speed falls outside the direct explanation of Bernoulli's principle. Thus, recognizing how Bernoulli's principles govern the airflow and pressure around airfoils is fundamental for pilots and engineers alike.