What connects newtons three laws?

Answer 1

Newton's laws all have to do with forces. The first says that if the net force on an object is zero, the object will experience no acceleration (its velocity will remain constant). The second says that the force on an object is equal to the rate of change of the object's momentum, or more commonly the object's mass times its acceleration. The third law describes action-reaction pairs, where any time an object A exerts a force on an object B, object B exerts a force of the same magnitude on object A.