I would call it the mistake of taking a theorem about Newtonian physics that was proven by assuming finitely many objects, and generalising it to infinitely many (which would be allowed by limits, but this isn’t using limits.
I’m confused. Are you saying that the CoM would accelerate in this situation, and thus the proof that CoMs only accelerate under external forces does not apply to this situation, or are you saying that this counterexample is misconstructed, and the CoM would not accelerate?
I’m confused. Are you saying that the CoM would accelerate in this situation, and thus the proof that CoMs only accelerate under external forces does not apply to this situation, or are you saying that this counterexample is misconstructed, and the CoM would not accelerate?
I thought I was saying the former, although I’m no longer actually sure.