A uniform rectangular block is moving to the right on a rough horizontal floor (the block is retarding due to friction). The length of the block is L and its height is `h`. A small particle (A) of mass equal to that of the block is stuck at the upper left edge. Coefficient of friction between the block and the floor is `mu = (2)/(3)`. Find the value of h (in terms of L) if the normal reaction of the floor on the block effectively passes through the geometrical centre (C) of the block.