Explain action and reaction of force:
Two bodies A and B are in contact at point 'O'. Body A
Press against body B. Thus action of body A on the body B is F. Reaction of the Body B on body
A is R. From the Newton's third law of motion (which is action = reaction), both the forces are equal there for
F = R
That is, Action = Reaction
Or, Any pressure on support causes an equal and opposite pressure from support such that action and reaction are two equal and opposite forces.