Hydrostatic Pressure

p = p_{0} + ρ g h = p_{0} + γ h

Pressure in a static fluid increases linearly with depth. Gage pressure at a free surface is zero. Resultant force on a plane area is F = p_cg A, acting at the center of pressure.

$ρ$ (kg/m³): Density
$h$ (m): Depth below the free surface
$γ$ (N/m³): Specific weight ρg

Step-by-step solved example

Gage pressure 5 m below a lake surface. ρ = 1000 kg/m³, g = 9.81.

p = ρgh. Pressure grows linearly with depth on a tank wall.

1. Compute
p = ρgh = 1000×9.81×5 = 49.05 kPa.
$p = 49.05 kPa (gage)$

Answer: 49.1 kPa gage

10 practice questions

0/10 correct

1.γ_water (SI) is about

2.10 m of water produces about

3.Absolute pressure is

4.Force on a 2 m² window 4 m to centroid in water ≈

5.Center of pressure on a vertical plane is

6.Manometer reading is independent of

7.Buoyant force equals

8.A floating body displaces its own

9.Vacuum of 30 kPa at atm = 101 kPa: p_abs =

10.Specific gravity of a fluid is