\[\text P_{p} \cdot \frac{d}{3}=P_{a} \frac{(H+d)}{3}\]
\[\frac{{{{\text{P}}_{\text{p}}}}}{{\text{FOS} }}\frac{{\text{d}}}{{\text{3}}}{\text{ = }}{{\text{P}}_{\text{a}}}\frac{{({\text{H + d}})}}{{\text{3}}}\]
\[\text P_{p} \frac{1}{2}=k_{p} \gamma d^{2}\]
\[\text P_{p} \frac{1}{2}=k_{p} \gamma(H+d)^{2}\]