Laws of motion

See Fig. 4.15. A wooden
block of mass 2 kg rests on a soft horizontal
floor. When an iron cylinder of mass 25 kg
is placed on top of the block, the floor yields
steadily and the block and the cylinder
together go down with an acceleration of
0.1 m s
–2. What is the action of the block
on the floor (a) before and (b) after the floor
yields ? Take g = 10 m s–2. Identify the
action-reaction pairs in the problem.