The barrier shown between two water tanks of unit width (1 m) into the plane of the screen is modeled as a cantilever.

Taking the density of water as 1000 kg/m³, and the acceleration due to gravity as 10 m/s², the maximum absolute bending moment developed in the cantilever is ______ kNm (round off to the nearest integer).

The correct answer is 105.

1. Hydrostatic Force on the Left Side:
From the first image, the water depth on the left side of the barrier is $h_1=4\text{m}$. The width of the barrier is $w=1\text{m}$.
The area of the submerged surface on the left is:
$A_1=4\text{m}\times 1\text{m}=4{\text{m}}^2$
The depth of the centroid from the water surface is:
${\overline{x}}_1=\frac{h_1}{2}=2\text{m}$
The total hydrostatic force acting on the left side is:
$F_1=\rho g{A}_1{\overline{x}}_1=1000\times 10\times 4\times 2=80\text{,}000\text{N}=80\text{kN}$
This force acts at the center of pressure, which is located at a height from the base (fixed support A):
${\text{CP}}_1=\frac{h_1}{3}=\frac{4}{3}\text{m}$

2. Hydrostatic Force on the Right Side:
From the first image, the water depth on the right side is $h_2=1\text{m}$.
The area of the submerged surface on the right is:
$A_2=1\text{m}\times 1\text{m}=1{\text{m}}^2$
The depth of the centroid from the water surface is:
${\overline{x}}_2=\frac{h_2}{2}=0.5\text{m}$
The total hydrostatic force acting on the right side is:
$F_2=\rho g{A}_2{\overline{x}}_2=1000\times 10\times 1\times 0.5=5\text{,}000\text{N}=5\text{kN}$
This force acts at the center of pressure, which is located at a height from the base (fixed support A):
${\text{CP}}_2=\frac{h_2}{3}=\frac{1}{3}\text{m}$

3. Maximum Absolute Bending Moment:
The maximum bending moment in a cantilever wall subjected to hydrostatic pressure occurs at the fixed base (A). Since the two forces act in opposite directions, their moments at the base oppose each other:
$M_A=F_1\times {\text{CP}}_1-F_2\times {\text{CP}}_2$
Substituting the calculated values:
$M_A=80\times \frac{4}{3}-5\times \frac{1}{3}$
$M_A=\frac{320}{3}-\frac{5}{3}=\frac{315}{3}=105\text{kNm}$