\(12 gh -3 gh =\frac{1}{2} 3 v ^{2}+\frac{1}{2} 12 v ^{2}+\frac{1}{2}\left[12 r ^{2}\right]\left(\frac{ v }{ r }\right)^{2}\)
\(9 gh =\frac{1}{2}[3+12+12] v ^{2}\)
\(v ^{2}=\frac{2 gh }{3} \Rightarrow v =\frac{1}{2} \sqrt{\frac{8}{3} gh }\)
\(x =\frac{8}{3} \simeq 3\)