CR-21 Landscapes and Irrigation Practice Test

The amount of pressure from a column of water grows with the height of the column. In US units, the weight density of water is about 62.4 pounds-force per cubic foot. Pressure in pounds per square foot is this weight density times the height: P(psf) = 62.4 h. To get psi, convert from psf to psi by dividing by 144 (since 1 ft^2 = 144 in^2). So P(psi) = (62.4 h) / 144 ≈ 0.433 h. That means each foot of head adds about 0.433 psi. The other numbers don’t fit: 2.31 is the reciprocal in this context, 1.0 ignores the conversion, and 3.14 has no relevance here.