A solid cube of wood of side 2a and mass M is resting on a horizontal surface as shown in the figure. The cube is free to rotate about a fixed axis AB. A bullet of mass m (<<M) and speed v is shot horizontally at the face opposite to ABCD at a height 4a/3 from the surface to impart the cube an angular speed ω. It strike the face and embeds in the cube. Then ωc is close to (note : the moment of inertia of the cube about an axis perpendicular to the face and passing through the center of mass is 2Ma2/3)
(A) Mv/ma
(B) Mv/2ma
(C) mv/Ma
(D) mv/2Ma
