The force of friction and the weight of the pages combine, tightly binding the phone books together and making separation impossible for a single person. Tearing two interlaced phone books apart using two 18 wheeler. Why cant you separate interleaved books physics today. In fact, if the experiment is done at a larger scale using two phone books, those phone books can even be attached to a crane to lift the weight of an entire car. The aim of our experiment is to illustrate the friction force in a dramatic way and to simplify the tedious job of interleaving a large number of book pages, by using the minimum number of sheets.
You may be interested to know that the task of pulling apart two humble phone books laying face up with their pages interleaved like a shuffled deck of cards is nearly impossible. When a few pages are interleaved, you may find the books pull apart easily. For example, almost every movement you make, such as walking and running, involves friction. A remarkable demonstration of the influence of friction involves a pair of phonebooks with their pages interleaved. Physics the strength of interleaved phonebooks explained.
Can you lift a car using two interleaved phone books. Friction and gravity exist in every aspect of a persons life. Now repeat this process for as many pages as are in a phone book, and youve got a lot of friction. All that is holding the two books together is friction. Explore friction by launching stuff, from scientific. Dec 09, 2015 many people are familiar with the friction enigma of two interleaved phonebooks, in which all of the pages of two phonebooks are overlapped, one by one, with the books spines facing. Phone book paper is on the rougher side, probably 0. Researchers explain why its nearly impossible to separate two. Researchers explain why its nearly impossible to separate. Then interleave the pages and try to pull the books apart. Phone book friction, from mythbusters the enigma of the two interleaved phonebooks pdf, from cornell university library slippery science.
After all, youre pulling on the spines of the books and friction directly. But the results change as you interleave more and more pages. The more pages you add, the larger this effect becomes. Friction, good people, is a wonderfully powerful force. With spencer heney, cristina magirescu, stephanie kollmar, roubina karina. The pages of the sticky note pads are held together by friction. Shuffle two phone books together like a deck of cards. Aug 20, 2018 in this paper we describe a simple alternative to the telephone book friction experiment, a classic demonstration where a small force generated for example by the bending of the outer pages is amplified by the large number of surfaces in contact, resulting in a huge maximum static friction force that has to be counterbalanced in order to. When you intertwine two notebooks, page by page, they become inseparable books. There are sliding friction experiments, a phone book friction experiment, a way to make rice stick together, an experiment to create frictional heat, and lots more friction experiments for all ages. A new experiment shows it is even possible to suspend a car from them. It is impossible to separate two interlocked phone books due to the massive amount of friction between the 800 pages of each book. For two books of pages each there are 1999 pagesurfaces in contact. Its a fascinating read, and its all to do with friction.
Using a model that reproduces the traction and friction forces involved, researchers have shown that when the spines of the interleaved phonebooks are pulled on vertically, part of the vertical. In the case of friction at single interface then its true that increasing the surface area doesnt generally help much, as force is spread over a larger area in parallel and, as a previous poster said, the reduction in. In this paper we describe a simple alternative to the telephone book friction experiment, a classic demonstration where a small force generated for example by the bending of the outer pages is amplified by the large number of surfaces in contact, resulting in a huge maximum static friction force that has to be counterbalanced in order to. May 01, 2008 when the force of friction covers a big area, it becomes very strong. The more pages you put together, the bigger the area and the more friction you create.
Fighting childrens misconceptions with the fantasticfour. This ensures that we are testing the strength of the frictional forces between the pieces of paper and not the forces of the c clamps. Though a familiar concept, friction is a subject worthy of much more scientific study and the physicists behind this phone book trick have taken the time to point out some of the ongoing research on friction in modern science. Summing all of this, we would expect the interleaved phone books to exhibit times the friction that noninterleaved phone books exhibit. The scientists explain that this tiny force on the outermost pages. Physicists solve the mystery of interleaved phone books. First, some context, in case you are a child of the 21st century, and so perhaps have no personal experience with paper telephone books, which could be hefty.
Mystery of why interleaved phone books cant be pulled apart. Try pulling apart two interleaved phone books and youll inevitably be. The interleaved portions of the post it notes should be free from clamps. In relation to this interleaved phone book the normal force is applied to all the pages in series instead of in parallel. A famous demonstration of the counterintuitive power of friction involves two telephone directories with their pages alternately interleaved. This is exactly what the team investigating the friction of phone books did. Mad scientist, david willey, with the help of his friends ed and kurt, tear apart a pair of interleaved phone books. The more pages you put together, the bigger the area and the more friction you. If each phone book is 500 pages, then when you interleave them you are putting pages on top of each other. A pair of cars also failed at pulling the phone books apart.
Now french researchers have performed experiments with smaller booklets and developed a mathematical model that explains why. When the force of friction covers a big area, it becomes very strong. The suggestion that two interleaved phone books cannot be pulled apart is more complex than it seems. Aug 28, 2015 so begins the article over at the conversation, explaining why its impossible to pull apart interleaved phone books. Feb 19, 2017 mythbusters phone book friction video this is a short video clip from the episode of mythbusters on the discovery channel. Many people are familiar with the friction enigma of two interleaved phonebooks, in which all of the pages of two phonebooks are overlapped, one by. Why it takes tanks to separate two phone books the pipettepen. Check out the latest episodes of science friction, the show that breaks down the real science behind scifi and comic book superpowers and explains how an ordinary human being like.
Why its impossible to pull apart interleaved phone books. Summing all of this, we would expect the interleaved phone books to exhibit times the friction that non interleaved phone books exhibit. Take two phone books, each about 1 kg about pages and carefully shuffle the pages together, each page of one phone book alternating with a page of the other phone book. Inseparable books experiments steve spangler science. Students take turns trying to pull apart two interleafed phone books. Check out this handson activity and see if you can overpower the friction between the books. A few years ago, an episode of mythbusters explored the strength of interleaved phone books. Aug 26, 2015 finding an approximate solution to a complex problem is an essential skill in science and in life. Demonstrating the power of friction with phonebooks youtube. See more ideas about force and motion, physical science and science experiments. How to do a friction science experiment science experiments. Graphs, observations, procedures all of science falls by the wayside without a way of recording the information. It is an old barroom trickmaking a nexttoimpossible task seem easy.
Jun 20, 2017 test which surfaces create more friction, see how strong friction is, learn how to reduce friction, and even discover the side effects of friction. Take two phone books and lie them face up, with the spines facing away from each other. The interleaved phonebook demonstration is important because it is just one. A famous demonstration of the counterintuitive power of friction. If there are 999 pages in total in contact with each other, the friction between the pages is equal to 500 times the friction between one book and a table. Even a small number of interleaved pages can result in a surprisingly large amount of friction, making the sticky notes impossible to pull apart. Tension results in a compression at the middle that results in a goodsized normal force, and hence a goodsized static friction force. The friction between the pages can be so great that a car can be suspended from such a phonebook pair. This results in a huge increase in the friction force, making them nearly impossible to pull apart. The fact that the pages of two phone books are interleaved means that friction as well. Many people are familiar with the friction enigma of two interleaved phonebooks, in which all of the pages of two phonebooks are overlapped, one by one, with the books spines facing. First, some context, in case you are a child of the 21st century, and so perhaps have no personal experience with. Table 1 shows the static friction coefficients for some common materials. This type of braid is applicable to sutures in surgery 30, and is also thought to play a role in adhesive proteins 31.
The ground and other solid surfaces can cause friction, called dry friction, but fluids liquids and gases like water and air can also cause frictional forces, called fluid friction. Mythbusters phone book friction video this is a short video clip from the episode of mythbusters on the discovery channel. The mythbusters tried to pull the two phone books apart with human power, which was unsuccessful. The backoftheenvelope answer is friction between the pages. A person sliding a book across a table creates friction. The first factor is reminiscent of the selfamplification of friction in a capstan 19, as well as in interleaved assemblies of sheets 20, 21, where the increase in resistance is created by. So the clamps just bind to the top of each section, the part that does not have the other sides pages interleaved. Aug 17, 2015 a famous demonstration of the counterintuitive power of friction involves two telephone directories with their pages alternately interleaved. Friction is also the reason you can hold a book, and the reason why you dont slip when walking. Crucial to the geometrical ampli cation of friction with interleaved books are the angles n that the sheets make as they approach the contact region.
Why cant two interleaved phone books be pulled apart. It contains thirteen essays about personal barriers and biases that plague and propel science, especially when scientists push against the unknown. The friction force generated by the two interleaved phone books on the left is enough to support a car. In this episode they tried to bust the myth that it is impossible to pull two interleaved phone books apart.
It would be a great video to show at the beginning of the study of friction to grab the students attention and get them interested and thinking. Physicist kari dalnokiveress did his own interleaved phone book mythbuster experiment and recruited students to help him demonstrate the. Mar 11, 2020 the interleaved portions of the post it notes should be free from clamps. There are sliding friction experiments, a phone book friction experiment, a way to make rice stick together, an experiment to create frictional heat, and lots. The fact that the pages of two phone books are interleaved means that friction as well as weight is preventing them from being separated. Test which surfaces create more friction, see how strong friction is, learn how to reduce friction, and even discover the side effects of friction. When you pull on the phone books, the pages want to straighten out to be in the direction of the force. Check out the latest episodes of science friction, the show that breaks down the real science behind scifi and comic book superpowers and explains how an ordinary human being like you can become superhuman. Astonishingly, it turns out to be practically impossible to separate two interleaved phone books by pulling on their spines, however much force is applied. A simple alternative to the phone book friction demonstration. The researchers compared this selfinduced friction amplification effect to the. Physicists solve the mystery of interleaved phone books mit.
People have tried pulling two interleaved phone books apart by playing tug. Dec 16, 2015 using a model that reproduces the traction and friction forces involved, researchers have shown that when the spines of the interleaved phonebooks are pulled on vertically, part of the vertical. How to do a friction science experiment test which surfaces create more friction, see how strong friction is, learn how to reduce friction, and even discover the side effects of friction. Coefficients of static friction for a few common materials. To demonstrate how strong the force of friction can be, i use an activity developed by the mythbusters tv series, called phone book friction discovery 2008. Jan 07, 2016 a remarkable demonstration of the influence of friction involves a pair of phonebooks with their pages interleaved. Key to the phenomenon of spectacular friction forces between two interleaved phone books is a simple geometrical conversion of the traction force to an orthogonal component which. When you throw a ball up, gravity causes the ball to fall down. Oct 22, 2015 phone book friction, from mythbusters the enigma of the two interleaved phonebooks pdf, from cornell university library slippery science.
Key to the phenomenon of spectacular friction forces between two interleaved phone books is a simple geometrical conversion of the traction force to an orthogonal component which enhances the load and thus the friction. So begins the article over at the conversation, explaining why its impossible to pull apart interleaved phone books. It can be tempting in science, and in life, to believe that every stone has. Selfamplification of solid friction in interleaved assemblies. Finding an approximate solution to a complex problem is an essential skill in science and in life. A haphazard partyride to mexico evolves into an enigma with a fugitive alien at the helm. Jan 08, 2016 astonishingly, it turns out to be practically impossible to separate two interleaved phone books by pulling on their spines, however much force is applied. The thickness of the doubledup phone books where the pages interleave is twice as thick as the individual phone books at the binding. It crops up in the automotive word all the time, be it associated with tires, brakes and engine internals, or even the microtug of a. Science friction is a collection of articles written by mr. Each page in contact has the friction caused by the weight of the pages above it pushing down. Where the known meets the unknown is a 2004 book by michael shermer, a historian of science and founder of the skeptics society. Physics experimentpresentation on the friction between two phone books where the pages have been interleaved. People are then invited to pull the directories apart.
32 1671 122 960 1207 393 1614 178 715 160 1687 846 785 1676 1006 1608 523 971 417 1470 505 474 63 1058 1558 336 1598 358 1263 1551 421 406 1008 1491 291 67 230 381 521 773 1447 1471 79 1255 463 1196 1301 929