translation.en: KS: So I'm sure all you engineers know that even though aluminum is a metal, it's not a magnetic material. But something unexpected happens when you drop a magnet down an aluminum tube.
translation.zh: KS：我相信大家都知道虽然铝是一种金属， 但是却不具有磁性。但是，当你将一块磁铁从铝管中穿过时， 会有意想不到的事情发生。