dynamic pressure

Meaning: Dynamic pressure is the term ½ρv² in Bernoulli's equation, the kinetic energy per unit volume of a flowing fluid. It has units of pressure and grows with the square of speed, so doubling v quadruples it. For an ideal fluid (incompressible, nonviscous, steady streamline flow), the sum of the three terms stays constant along a streamline. When a pipe narrows, continuity (A₁v₁ = A₂v₂) raises the speed, so dynamic pressure rises and static pressure falls if height is unchanged.

Equation: P + ρgh + ½ρv² = constant, where P is static pressure (Pa), ρ is fluid density (kg/m³), g is gravitational acceleration (m/s²), h is height (m), and v is flow speed (m/s). Dynamic pressure is ½ρv² (Pa).

On the MCAT: A passage describes a Venturi tube, a narrowed artery, or air moving over a wing. You compare pressures in wide and narrow sections, or compute P₁ − P₂ = ½ρ(v₂² − v₁²) for a horizontal pipe, often after finding v from continuity.

Common confusion: Students think faster flow means higher pressure. Only the dynamic part rises; the static pressure, which pushes on the walls, drops, and the total is conserved. Bernoulli's equation assumes ideal flow. In a real viscous fluid, friction removes energy, so total pressure falls along the pipe.