What about the red cube in professor Lewin's lecture n.6?why did the bottom string break when he pulled fast and the upper when he pulled slower?

Question

anonymous · Answer

Is there any way this thread can be opened? I have no idea why it's closed. I had the same question, as well. I was in fact about to post it but I saw this post!

anonymous · Answer

Sorry,I closed the question because I saw it had already been asked and answered (in "closed questions"). Actually I'm not so sure about the answer, it's about the inertia of the block