## Top View
15. As shown in the top view above, a disc of mass m is moving horizontally to the right with speed v on a table with negligible friction when it collides with a second disc of mass 2 m The second disc is moving horizontally to the right with speed v/2 at the moment of impact The two discs stick together upon impact The speed of the composite body immediately after the collision is
(A) v/3
(B) v/2
(C) 2v/3
(D) 3v/2
(E) 2 v