Maybe we all played this game when we were children. Take some plastic bottle caps, put them on the table, and then strike the table hard, and the bottle caps will jump. On the contrary, if we pat the table from below, the bottle cap will also jump. What is the reason? The table itself does not seem to move. How to jump the bottle cap? It turns out that the table vibrates as soon as we strike it. Although this kind of vibration is not obvious, it is actually a high-speed fine movement, which can produce great power. This force pushes the bottle cap upward. This is a seemingly hard substance. In fact, soft matter is the same. We think of cigarettes as bottle caps and the other side of the cigarette case as a desktop. Now, if we hit the cigarette case (desktop) from the other side, the cigarette (bottle cap) will jump out. There is also a common sense that if a pack of cigarettes is full, it will be more difficult for cigarettes to jump out, because there will be friction between cigarettes, which will pull each other and it will take more strength to jump out. Take the bottle cap as an example to describe this point. Tie several bottle caps together with thin thread. Or you can stick the bottle cap together with some paste), and then strike the table, the bottle cap will not jump easily. In addition, in fact, this experiment can be done whether it is a soft-packed cigarette or not, but the hard-packed cigarette is more tightly packed and has great friction. If you take apart the hard-packed cigarettes and take out a few more, they will come out immediately.