In the side wall of the tank, where there is an overpressure (\( p_n = 200 hPa \)), there is a rectangular opening with dimensions \( a \times a/2 \). The opening is closed with a flat flap using a float in the shape of a prism with a regular hexagonal base of side length c and height f. The float has a mass of \( m_p = 10 kg \). The water elevation above the axis of rotation of the flap is \( H \). What volume \( V \) must the float have in order to ensure the closure of the opening when the float is completely submerged?
Data:
\begin{aligned} &a=0.8 m\\ &b=1 m \\ &c=0.7 m\\ &H =2 m\\ \end{aligned}