a cubical block of side a moving with velocity v on a horizontal smooth plane hits a ridge at point o. angular speed of block after it hits o is

Initial angular momentum of the block,
$L_i=Mv\times AC=\frac{1}{2}Mva$
Angular momentum of the block after it hits the point O,
$L_f=I_o\omega$
From Parallel axis theorem,
$I_o=I_c+M\times O{C}^2=\frac{1}{6}M{a}^2+M\times \left(A{C}^2+A{O}^2\right)=\frac{1}{6}M{a}^2+\frac{1}{2}M{a}^2=\frac{2}{3}M{a}^2$
Using conservation of Angular momentum,
$$\begin{gathered} \frac{1}{2}Mva=\frac{2}{3}M{a}^2\omega \\ \Rightarrow \omega =\frac{3v}{4a} \end{gathered}$$