# What is the pressure of a water tank that measures 13 ft. square by 14 ft. deep?

5.2 psi

Explanation

Pressure is equal to force per unit area or $$\frac{F}{A}$$ . For water, $$F = w \times d$$where w is the weight of water and d its depth. Water weighs $$62.4\frac{{lb.}}{{ft{.^3}}}$$ so:

$$w \times d=62.4 \frac{\mathrm{lb.}}{\mathrm{ft.}^{3}} \times 14 \mathrm{ft.}=873.6 \frac{\mathrm{lb} .}{\mathrm{ft.}^{2}}$$

The area (A) of the pool is $$13 \mathrm{ft} . \times 13 \mathrm{ft} .=169 \mathrm{ft} .^{2}$$ so:
$$P=\frac{F}{A}=\frac{873.6 \frac{ib.}{f t^{2}}}{169 f t^{2}}=5.2 p s i$$