Chapter 1 - Section 1.12 - Modeling Variation - 1.12 Exercises - Page 128: 40

$$1305.6 lb$$

According to the problem, we have: $L=ks^2A$ Where $k$ is constant of proportionality We have the following: $A=500 ft^2$ $s=50mi/h$ $L=1700lb$ $k$ is unknown $1700=k\times 50^2 \times 500$ $k=\frac{1700}{2500\times500}=\frac{17}{12500}=0.00136$ So, if $A=600ft^2$ $s=40mi/h$ $L=0.00136\times 40^2 \times 600=1305.6 lb$