What does static head refer to in fluid pressure terms?

• A. Vapor pressure
• B. Pressure from a pump
• C. Pressure difference
• D. Pressure due to height of the fluid above a reference point

Answer: (D)

Static head is the pressure produced by the weight of the liquid column above a point when the fluid is at rest. In a static fluid, pressure increases with depth because each layer bears the weight of what’s above it. This pressure at a location depends on the fluid’s density, gravity, and the vertical height of the fluid above the reference point, and is described by p = ρ g h. So static head is the pressure arising from the height of the fluid column above that point.

Vapor pressure is about how readily a liquid’s molecules escape into the gas phase, not the hydrostatic pressure from a fluid column. Pressure from a pump describes energy added to drive flow, not the resting pressure due to height. A pressure difference refers to a gradient between two points, not the absolute static pressure at a single point.