Chapter 5.4, Problem 3E

EXERCISE

River flow The cross sectional area $C$, in square feet, of a river is given by the formula

$C=wd$,

where, $w$ is the width of the river and $d$ is the depth, both in feet(See Figure 5.58). The speed $s$ of the flow, in feet per minute, is measured using a meter. The flow rate $F$, in cubic feet per minute, of the river is given by

$F=sC$

a Find a formula that gives $F$ in terms of the variables $w,d$, and $s$.

b Use the formula you found in part a to find the flow rate of the river that has a width of $23$ feet, a depth of $2$ feet, and flow speed of $24$ feet per minute.