\({h_1}\)= 80 mm ; \(\eqalign{& \rho = {10^3}(Kg/{m^3});{\sigma _1} = 0,072(N/m) \cr & {h_2} = .?..;{\rho _2} = 790(kg/{m^3});{\sigma _2} = 0,022(N/m) \cr} \)
\({h_1} = {4 \over {gd}}.{{{\sigma _1}} \over {{\rho _1}}};{h_2} = {4 \over {gd}}.{{{\sigma _2}} \over {{\rho _2}}}\)
\( \Rightarrow {{{h_2}} \over {{h_1}}} = {{{\sigma _2}{\rho _1}} \over {{\sigma _1}{\rho _2}}} \Rightarrow h_2= {{{h_1}.{\sigma _2}.{\rho _1}} \over {{\sigma _1}.{\rho _2}}} = {{80.0,{{022.10}^3}} \over {0,027.790}}\)
\(= 30,9(mm)\)
