Drag Force: The force that opposes the motion of an object moving through a fluid, such as air or water. The drag force is directly proportional to the cross-sectional area of the object.
Hydraulic Pressure: The pressure exerted by a fluid, such as water, on the surfaces it contacts. According to Pascal's Principle, the pressure applied to a confined fluid is transmitted equally in all directions, and the cross-sectional area of the fluid plays a role in this transmission.
Fluid Dynamics: The study of the motion of fluids and the forces acting on objects within those fluids. The cross-sectional area of an object is a key parameter in fluid dynamics, as it determines the resistance and flow patterns experienced by the object.