A cubical block of side a is moving with a velocity v on a smooth horizontal plane as shown. It hits a ridge at point O. The angular speed of the block when it hits O is

Question

 

\[\begin {array} {1 1} (a)\;\frac{3v}{4a} & \quad (b)\;\frac{3v}{2a} \\ (c)\;\frac{\sqrt 3 v}{\sqrt 2 a} & \quad  (d)\;zero \end {array}\]