The question "what happens when an unstoppable force meets an immovable object?" has been a perennial favorite in philosophical debates. The answer to this question, like all paradoxes, is that it depends on the perspective you take on the two objects in question. From a physics standpoint, for example, there is no such thing as an unstoppable force because the only way something can be unstoppable is if it has infinite energy, which in turn means that the force cannot be stopped or decelerated.
But from a metaphysical viewpoint, the answer is different. An unstoppable force is merely an idea. It is not assigned to mean any force, and it cannot be stopped or accelerated. Hence, the unstoppable force would simply continue to move, but in a different direction, depending on the reference frame that is used.
This is an old paradox that has had people doing all sorts of mental gymnastics in order to come up with some sort of sensible answer. The problem is that, according to physics, the whole concept of an "unstoppable force" and "irresistible object" makes no sense.
If there were an unstoppable object, it would require all the energy in the universe (and then some). And if there were an irresistible force, it would need to have infinite mass, which again, makes no sense at all. The only possible solution to this paradox is for a third party to be added to the situation in order to judge which of the two objects is truly unstoppable. But that's another story for a different article.