Block A rests on block B, which lies on a flat frictionless surface. There is friction only between the two blocks. If I were to exert on block A a horizontal force of magnitude less than that of the maximum static frictional force between the two blocks so that for block A Fnet,x=0, then block B would receive an equal frictional reaction force in the opposite direction. That block A would remain stationary while block B would accelerate in the direction of the force is clearly counterintuitive. Can someone please point out the flaw in my thinking? Thanks!