Question

A square lamina (each side equal to 2m) is submerged vertically in water such that the upper edge of the lamina is at a depth of 0.5 m from the water surface. If the pressure on the surface is 12 bar, what will be the total water pressure (in kN) on the lamina?

(a) 39

(b) 59

(c) 64

(d) 71

This question was addressed to me by my college professor while I was bunking the class.

The above asked question is from Hydrostatic Force on Plane Area in section Hydrostatic Forces on Surfaces of Fluid Mechanics

Answer 1

Right answer is (c) 64

Explanation: Total liquid pressure on the lamina = F = γyA, where γ = specific weight of the liquid, y = depth of centroid of the lamina from the free surface, A= area of the centroid. Now, γ = 9.81 * 10^3 N / m^3;  A = 2 * 2 = 4 m^2. Hence, F = 63.65 kN.