What primarily determines the lift generated by an airfoil?

The lift generated by an airfoil is primarily influenced by the angle of attack and the velocity of the airflow over the airfoil. The angle of attack refers to the angle between the chord line of the wing and the oncoming airflow. As the angle of attack increases, the lift also tends to increase up to a certain point, allowing the airfoil to generate more lift by increasing the airflow velocity over the upper surface of the wing, thereby lowering the pressure according to Bernoulli's principle.

Velocity plays a critical role as well; as the speed of the airflow increases, the lift generated by the airfoil also increases. This relationship is described in the lift equation, which includes terms for air density, velocity, wing area, and lift coefficient. In essence, both the angle of attack and the velocity work in tandem to maximize lift at any given moment, with slight variations able to significantly impact overall aerodynamic performance.

Thus, the combination of angle of attack and velocity is fundamental in understanding how lift is generated, making it the correct choice for this question. Other factors like air density and aspect ratio contribute to the lift as well, but they do not have as direct an impact as the angle of attack and velocity.