The fundamental physical laws governing the forces acting on an aircraft in flight, and effects these natural laws and forces have on the performance characteristics of aircraft. To control an aircraft, the pilot must understand the principles involved and learn to use or counteract these natural forces.
PHAK Ch-04
PHAK Ch-05 Forces Acting on the Aircraft Pages 1-8
PHAK Ch-05
Aerodynamic Forces in Flight Maneuvers Pages 22-25