What type of pressure is defined as gauge (water) pressure plus atmospheric (air) pressure)?

• A. Absolute
• B. Gauge
• C. Atmospheric
• D. Hydrostatic

Answer: (A)

Absolute pressure is the total pressure at a point, combining the water pressure caused by depth with the atmospheric pressure from the air above. Gauge pressure is just the water pressure above atmospheric, so it excludes the air’s pressure. Atmospheric pressure is the air’s pressure at the surface, not the total underwater pressure. Hydrostatic pressure refers to the pressure within the fluid due to gravity, essentially the water portion, not including the air pressure.

So, when you define pressure as gauge plus atmospheric, you’re describing absolute pressure—the total pressure you experience underwater.