Solution

The pressure on the faces of the prism:

$$P = \rho \cdot g \cdot h = 2 \cdot 10^5 ~ \text{Pa}.$$

Since the dimensions of the prism are small compared with the depth, we consider the pressure constant over its entire height.

The pressure forces on the front and bottom faces are equal and are determined by the hydrostatic pressure $P$ and the area of a face of the prism:

$$F_1 = F_2 = P \cdot a^2.$$

Since the two faces are perpendicular, we find the resultant force using the Pythagorean theorem:
$$|F_{\text{R}}| = \sqrt{F_1^2 + F_2^2} = 2000 \sqrt{2} ~ \text{N}$$

According to Pascal's law, the pressure is balanced, and the resultant force:

$$F_{\text{sum}} = 0.$$