Question $-($ANSWERS PROVIDED$)$

$($a$)$ The drag force acting on the panel $-$ ANSW $(18,000$N$)$

$($b$)$ The drag force acting on each pole $-$ ANSW $(68$ N$)$

$($c$)$ Minimal length L of the concrete block $-$ ANSW $(3\mathrm{.}70$ m$)$