Question

Hydraulicists often express rainfall in acre-feet. this is the amount of water required to cover an area of one acre to a depth of one foot. there are 640.0 acres in a square mile, and 5280 feet in one mile. how many cubic feet are there in one acre-foot?

Answer 1

1 sq.mile
= (5280 ft)^2
=27878400 ft^2

Since 1 sq. mile contains 640 acres, therefore
1 acre
=27878400 ft^2 / (640 acres / sq. mile)
=43560 ft^2/acre

This means the volume of 1 acre-foot
= 43560 ft^2 * 1 ft
= 43560 ft^3

Answer 2

1 acre foot = 43560 ft³

Explanation:

1 square mile = 640 acres.

5280 feet = 1 mile

5280 x 5280 ft² = 640 acres.

1 acre = 43560 ft².

1 acre foot = 43560 x 1 ft³ = 43560 ft³

1 acre foot = 43560 ft³