## Question:

Determine the equivalent resultant force acting on the bottom of the wing due to air pressure and specify where it acts, measured from point $A$.

Given:

$a$ = $3$ $ft$

$k$ = $86\frac { Ib }{ { ft }^{ 3 } }$

$w(x)$ = $k{ x }^{ 2 }$

## Step-by-step

${ F }_{ R }$ = $\int _{ 0 }^{ a }{ w(x)dx } \quad \quad \quad \quad { F }_{ R }$ = $774$ $Ib$

$x$ = $\frac { \int _{ 0 }^{ a }{ xw(x)dx } }{ { F }_{ R } } \quad\quad \quad \quad \quad x$ = $2.25$ $ft$