Which concept relates to pressure caused by the motion of fluid, not by its static pressure?

• A. Dynamic pressure
• B. Static pressure
• C. Surge/hammer
• D. Friction Loss

Answer: (A)

Dynamic pressure is the pressure that comes from the fluid’s motion—the kinetic energy per unit volume of moving water. It depends on velocity and grows with the velocity squared (dynamic pressure equals 1/2 ρ v^2). If you could bring the moving water to a stop, the amount you’d “add” to the pressure is this dynamic component. In contrast, static pressure is the pressure exerted by the fluid regardless of movement. In many systems you can relate the total pressure to static pressure plus velocity head (dynamic pressure). So the pressure arising specifically from how fast the water is moving is dynamic pressure, not static pressure. The other concepts describe either the pressure level when there’s no motion (static), transient spikes from rapid changes (surge/hammer), or energy losses due to friction along the pipe (friction loss).