Monday, January 18, 2016
We Finally Know Why It's So Damned Hard to Pull Phone Books Apart
gizmodo.com: Several years ago, the Mythbusters famously tried to separate two thick phone books with pages tightly interleaved. They couldn’t do it. Scientists know it’s due to the enormous amounts of friction being generated, but precisely how this friction arises is a longstanding mystery. A new paper by French researchers concludes that it all comes down to the number of pages, their thickness, and the size of the overlap (contact) region between sheets.
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3 comments:
I found this article really fascinating, and a really good explanation of how this seemingly complex or mysterious process works in real life. If you haven’t seen the videos of the Mythbusters using two tanks to rip apart two phonebooks, you definitely should go watch it. Understanding these kinds of forces is pretty difficult without that context. Anyway, I was also surprised at the explanation given, particularly the fact that the pages not being parallel is the key to the whole thing. It make sense when you draw it out and think about it, but it was counterintuitive to my mind. Now I’m struggling to find an application for this very particular niche in science and engineering that we would find valuable in the theatre, but I’m sure the knowledge of how this kind of friction works would be a valuable thing when trying to design a contraption that depends on friction, or the lack of it for that matter.
I loved this episode of Mythbusters, and I'm glad that someone actually did research on the precise forces that are involved. The larger picture of the physics involved in the phonebook experiment isn't complicated, and the answer seems pretty obvious. Of course the number of pages and area of overlap are factors in the amount of friction between them. But it is interesting to note the additional forces created by the angle of the pages as they join the binding, which is something that I hadn't considered.
I'm not really concerned with how this knowledge is useful in any way, because like many things this is interesting to know just for the sake of knowing. Maybe it's a good party fact. But one of my favorite things about Mythbusters is that a lot of their experiments and research has little to no practical application: but now they know. This falls in the same category as knowing if a horse can pull the bars out of a prison window in a western movie. They can't, FYI, but it's a fun party fact.
I love this story. This is a case where truth is stranger than fiction. The fact that the interwoven pages of a phonebook creates so much friction is astounding. I think setting up a phonebook swing would make a great playground piece. The fact that friction is the key is not surprising, but the interesting part of this is exactly how the friction works. The angle of the interwoven pages to the spine is something that I never would have thought of. The friction between the pages is easy to see, but the fact that pulling them apart acts on the angle of the friction so interesting. And that’s what the Mythbusters do best. They take stories and find out what’s involved, what makes them work, and combine science and entertainment. In this case, the story directly applies to theater in that friction has to be taken into account when working with moving scenery.
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