Dynamic pressure is proportional to air density and the square of velocity.

• A. Proportional to density and velocity squared
• B. Proportional to density only
• C. Proportional to velocity only
• D. Independent of density

Answer: (A)

Dynamic pressure represents the kinetic energy of the moving air per unit volume, and it follows the relation q = 1/2 ρ V^2. This shows that dynamic pressure depends on both how dense the air is and how fast the air is moving relative to the aircraft. If the air becomes denser, dynamic pressure increases proportionally; if you double the speed, dynamic pressure increases by a factor of four. This is why dynamic pressure is central to many flight reasons, such as influencing lift (through L = q S Cl) and being what a Pitot tube measures as part of the total pressure. The other ideas miss either the speed term, the density term, or ignore the density dependence entirely, which conflicts with the fundamental equation.