You're presented with a column of water three feet by three feet, with a height of one foot, the water pressure of this column equals:

• A. 0.217 PSI
• B. 0.434 PSI
• C. 0.869 PSI
• D. 1.0 PSI

Answer: (B)

Hydrostatic pressure depends only on how tall the water column is and the fluid’s weight per volume. The bottom pressure is P = γ h, where γ is the unit weight of water (about 62.4 pounds per cubic foot) and h is the height of the water above the point.

Here, h is 1 foot, so P = 62.4 × 1 = 62.4 pounds per square foot. Convert to psi by dividing by 144 (square inches per square foot): 62.4 / 144 ≈ 0.433 psi, which rounds to 0.434 psi.

The 3 ft by 3 ft cross-section doesn’t change the pressure itself; it would affect total force on a surface (F = P × A) but not the pressure at the bottom.