Newton’s Third Law states that when an object exerts a force on another object, both exert equal and opposite forces on each other.  Simply stated, for every action there is an equal and opposite reaction. This is called action and reaction forces.  These forces always happen in pairs.  The action force is one part of the pair. The reaction force is the other part of the pair that is equal in strength and opposite in direction to the action force.  For example, if object A exerts a force on object B, then object B must exert a force on object A.  Action and reaction must occur simultaneously.  Acceleration happens when the mass of the pair of forces is different and inversely proportional. A small produces a greater acceleration than the same force exerted on a large mass.