Hydrostatic Force acting on Submerged Surface

The thrust force acting on a surface submerged in a liquid can be calculated as

F = p_a A 

   =ρ g h_a A                           (1)

where

F = thrust force (N)

p_a = ρ g h_a = average pressure on the surface (Pa)

A = area of submerged surface (m²)

h_a = average depth (m)

ρ = density (kg/m³)  (water 1000 kg/m³)

g = acceleration of gravity (9.81 m/s²) 

Example - The thrust force acting on the side of a container

The trust force acting on the submerged vertical side of a container can be calculated as

F = p_a A 

   = ((p_t + p_b) / 2) A   

   = (ρ g (h_t + h_b) / 2) A                         (2)

where

p_t = pressure at the top of the submerged surface (Pa)

p_b = pressure at the bottom of the submerged surface (Pa)

h_t = depth at the top of the submerged surface (m)

h_b = depth at the bottom of the submerged surface (m)

The thrust on a surface with width 1 m and height from 0 m to 2 m - in a water-filled container can be calculated as

F =  (ρ g (h_t + h_b) / 2) A

   = (1000 kg/m³) (9.81 m/s²) ((0 m) + (2 m)) / 2) ((1 m) (2 m))

   = 19620 N

   = 19.6 kN

Example - The thrust force acting on the bottom of a container

The trust force acting on the horizontal bottom of a submerged container can be calculated as

F =  p_b A   

   = ρ g h_b A                                     (2b)

The thrust on a bottom with width 1 m and length 2 m - on depth 1 m - in a water filled container can be calculated as

F =  ρ g h_b A

   = (1000 kg/m³) (9.81 m/s²) (1 m) ((1 m) (2 m))

   = 19620 N

   = 19.6 kN

Temperature ^oC
K
^oF

Length m
km
in
ft
yards
miles
naut miles

Area m²
km²
in²
ft²
miles²
acres

Volume m³
liters
in³
ft³
us gal

Weight kg_f
N
lbf

Velocity m/s
km/h
ft/min
ft/s
mph
knots

Pressure Pa
bar
mm H₂O
kg/cm²
psi
inches H₂O

Flow m³/s
m³/h
US gpm
cfm