The drag force F on a boat varies jointly with the wet surface area A of the boat and the square of the speed s of the boat. A boat with a wet surface area of 50ft2 traveling at 7mph experiences a drag force of 98N . Find the wet surface area of a boat traveling 7.5mph and experiencing a drag force of 135N .
Accepted Solution
A:
[tex]\bf \qquad \qquad \textit{direct proportional variation}\\\\
\textit{\underline{y} varies directly with \underline{x}}\qquad \qquad y=kx\impliedby
\begin{array}{llll}
k=constant\ of\\
\qquad variation
\end{array}\\\\
-------------------------------\\\\
\begin{cases}
F=\textit{drag force}\\
w=\textit{wet area}\\
s=speed
\end{cases}\textit{\underline{F} varies jointly with \underline{w} and square of \underline{s}}\quad F=kws^2[/tex]