$11-96$ A $2-$m$-$high, $4-$m$-$wide rectangular advertisement panel is attached to a $4-$m$-$wide, $0\mathrm{.}15-$m$-$high rectangular concrete block $($density $=2300k\frac{g}{m^3})$ by two $5-$cm$-$diameter, $4-$m$-$high $($exposed part$)$ poles, as shown in Fig. P$11-96.$ If the sign is to withstand $150k\frac{m}{h}$ winds from any direction, determine $(a)$ the maximum drag force on the panel, $($b$)$ the drag force acting on the poles, and $($c$)$ the minimum length $L$ of the concrete block for the panel to resist the winds. Take the density of air to be $1\mathrm{.}30k\frac{g}{m^3}.$

FIGURE P$11-96$