A wooden block of mass 2 kg rests on a soft horizontal floor . When aniron cylinder of mass 25 kg is placed on top of the block , the floor yields steadily , and the block and the cylinder go down with an acceleration of `0.1 ms^(-2)` What is the action of the block on the floor (a) before and (b) after the floor yields ? Take `g = 10 ms^(-2)` . Identify the action reaction pairs in the problem .