Aerodynamics is defined as:

• A. The science of solids moving through air.
• B. The study of weather patterns affecting flight.
• C. The science of the action of air on an object, including lift, relative wind, and the atmosphere.
• D. The mechanics of propulsion systems.

Answer: (C)

Aerodynamics is the study of how air interacts with objects in flight. It focuses on the action of air on an object, including lift, relative wind, and the atmosphere. Lift is the upward force produced by how air flows around a wing, which depends on the wing’s shape and its angle of attack. Relative wind is the airflow that appears to come from the opposite direction of the aircraft’s motion and is what surfaces actually respond to as the plane moves through the air. The atmosphere provides the medium in which these effects occur and changes with altitude, influencing how air behaves around the aircraft.

The other descriptions don’t capture what aerodynamics studies: solids moving through air describes simply motion through a medium without addressing the air–surface interaction that creates lift and other forces; weather patterns are meteorology, not the forces on a moving aircraft; propulsion systems deal with producing thrust, not how air flow creates lift and other aerodynamic forces.