Why does a swept wing design reduce the effective airspeed of the wingtip?

A swept wing design reduces the effective airspeed of the wingtip primarily due to the angle of the wing sweep. When a wing is swept back, it changes the angle at which the airflow interacts with the wing. This angular relationship effectively alters the relative wind direction experienced by the tip of the wing. As a result, the component of airspeed that is perpendicular to the wingspan decreases at the wingtip compared to a straight wing.

This reduction in effective airspeed at the tip is crucial for delaying the onset of drag associated with supersonic flows and could also help in managing control and stability at high speeds. It allows aircraft with swept wings to perform better at higher operational speeds by reducing the likelihood of shockwaves forming on the wing's surface, which can significantly affect lift and drag characteristics. Additionally, the design is particularly advantageous for minimizing induced drag, leading to more efficient flight.

The other options do relate to aerodynamic principles, but they do not directly address the specific mechanics of how the geometry of a swept wing alters the effective airspeed at the tips. Therefore, the angle of the wing sweep stands out as the primary factor in this instance.