Question 3.P.19: Determine the resultant force on the wall of a tank ABC as s......

Considering unit width,

Horizontal force equals the force on the projected area = γ  A  \bar{h}

= 9810 × 4 × 2 = 78480 N

This force acts at 2.6667 m from the top

The vertical force equals the weight of the volume above the surface (unit width)

Vertical force       = 9810 × (4 × 2  –  π  2^{2}/4) × 1 = 47661  N (downward)

Resultant              = (78480^{2} + 47661^{2})^{0.5} = 91818  N

Angle with vertical  θ : \tan^{– 1}  (78480/47661) = 58.73°

To fix the line of action, the line of action of the vertical force should be determined.