What does "aerodynamics" study?

Aerodynamics is the branch of physics that focuses on the behavior of air and how it interacts with solid objects, especially when those objects are in motion. This field examines the forces of lift, drag, thrust, and weight as they relate to the design and performance of aircraft. Understanding these interactions is crucial for pilots and engineers alike, as it informs everything from aircraft design to flight performance.

The other options address different aspects of aviation. The performance of engines pertains to how the power units operate and contribute to an aircraft's flight, while the structure of aircraft involves the materials and physical configuration of the aircraft itself. The mechanics of landing relates to the procedures and techniques used by pilots when bringing an aircraft safely to the ground, which is a subset of aerodynamics but does not encapsulate the entire field. Thus, studying how air interacts with moving objects encompasses the essence of aerodynamics.