Which type of pressure is caused by the motion of a fluid?

• A. Static pressure
• B. Impact pressure
• C. Relative pressure
• D. Absolute pressure

Answer: (B)

Pressure generated by the movement of a fluid is dynamic (impact) pressure. This portion of pressure comes from the fluid’s velocity—the kinetic energy of the moving fluid gets converted to pressure when the flow is brought to rest, such as at a stagnation point. In aviation terms, a pitot tube measures this impact pressure as the difference between stagnation (total) pressure and static pressure, and it’s this dynamic pressure that relates directly to airspeed through q = 1/2 ρV^2. Static pressure is just the pressure in the fluid due to its position and motion-free state, absolute pressure is the total pressure relative to a vacuum, and relative pressure is the pressure above ambient. So the pressure caused by motion is the dynamic (impact) pressure.