Interleaved phone book friction experiment

People have tried pulling two interleaved phone books apart by playing tug. Inseparable books experiments steve spangler science. It is impossible to separate two interlocked phone books due to the massive amount of friction between the 800 pages of each book. 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. Can you lift a car using two interleaved phone books. 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. The mythbusters tried to pull the two phone books apart with human power, which was unsuccessful. In such a case, the books can be easily pulled apart, consistent with the theory presented. In effect, they set two phone books together, then pushed them into each other so that their pages alternated, and every page of one phone book was lying between two pages of the other. It is an old barroom trickmaking a nexttoimpossible task seem easy. Will tory and kari successfully pull apart two phone books in 30 minutes without breaking their teeth.

A new experiment shows it is even possible to suspend a car from them. The pages of the sticky note pads are held together by friction. The accumulated friction between the pages is so great that, as. But lets take it up a notch now and take two books full of ordinary paper, two ordinary books. Friction, good people, is a wonderfully powerful force. During this talk, we will present some funny experiments and, in particular discuss the phonebook story. Separating books experiment try pulling apart two interleaved books try pulling apart two interleaved phone books start off with two books the same size, interleave them together. Bring it to your classroom and watch the tugowar begin.

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 more carefully you set this up the better this trick works. This compressive force will create a frictional force between every place the pages are interleaved, if there are 50 interleavings a small frictional force will be multiplied by 50 to create a huge force that you cant overcome with pure muscle. We provide three control experiments to demonstrate the role of atmospheric pressure in the two book experiment and an additional simple. It is nearly impossible to sepa rate two interleaved phone books when held by their spines. The interleaved portions of the post it notes should be free from clamps.

Even a small number of interleaved pages can result in a surprisingly large amount of friction, making the sticky notes impossible to pull apart. Friction is the reason you cant roll a ball for eternity with one toss, but its also what enables you to run as you press your feet against the ground. Friction is an old story that is still modern despite of its importance. I set up a simple experiment to test the question if there are more forces at work than static friction. 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. Separating books experiment try pulling apart two interleaved books try pulling apart two interleaved phone books start off with two books the. Now french researchers have performed experiments with smaller booklets and developed a mathematical model that explains why the friction.

Phone book friction justin lazaro, tarissa miller, john biehle. A person sliding a book across a table creates friction. A remarkable demonstration of the influence of friction involves a pair of phonebooks with their pages interleaved. When drawing on the books spines, where the pages lie closer together than in the section where the two books are interleaved, a part of the pulling force actually increases this load and thus amplifies the friction force in a nonlinear way alarcon et al. Just calculate the force per page from the formula f coefficient of friction x normal force and then multiply this times the number of pages. View homework help phone book friction presentation. Why cant you separate interleaved books physics today.

Friction news, research and analysis the conversation. A simple alternative to the phone book friction demonstration. When pages n are interleaved, it can be assumed that all weights force. Explore friction by launching stuff, from scientific. Selfamplification of solid friction in interleaved assemblies. The phone books wouldnt come apart using all the mythbusters gadgets and even attaching the phone books between two cars. For example, almost every movement you make, such as walking and running, involves friction. Rolling friction is generally the weakest form of friction. Editorial tools and workflow web content management. With jamie hyneman, adam savage, tory belleci, grant imahara. A pair of cars also failed at pulling the phone books. A full understanding of this astonishing demonstration of solid friction in. Phone book friction, from mythbusters the enigma of the two interleaved phonebooks pdf, from cornell university library slippery science.

A famous demonstration of the counterintuitive power of friction involves two telephone directories with their pages alternately interleaved. In this phone book case however the area is increased by interleaving many friction surfaces so that the force is applied in series to all the surfaces without the corresponding decrease in pressure. Investigate friction as you try to separate interleaved books and spin objects to discover the effects of forces. This is exactly what the team investigating the friction of phone books did. 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. Astonishingly, it turns out to be practically impossible to separate two interleaved phone books by pulling on their spines, however much force is applied. Researchers explain why its nearly impossible to separate. On this episode of mythbusters adam and jamie take a fan mail film and use it to dial in on a phone book fable. When you throw a ball up, gravity causes the ball to fall down. Physics the strength of interleaved phonebooks explained. The accumulated friction between the pages is so great that, as figure 1 shows, even the weight of a car cannot pull the phone books apart. A full understanding of this astonishing demonstration of solid friction in complex assemblies remains elusive. A simple, striking experiment take two phone books, interleave their sheets, and attempt to separate the books by pulling on their spines.

The enigma of the two interleaved phonebooks and other. It is nearly impossible to separate two interleaved phone books when held by their spines. It crops up in the automotive word all the time, be it associated with tires, brakes and engine internals, or. We consider a factor that has not been part of the popular explanationatmospheric pressure. Friction and gravity exist in every aspect of a persons life. In this article we consider the wellknown demonstration of friction by two interleaved books. The force of friction and the weight of the pages combine, tightly binding the phone books together and making separation impossible for a. Friction is the force that opposes motion when two surfaces are in contact. The backoftheenvelope answer is friction between the pages. No matter how much force is applied within reason, no hammer of thor stuff you cant separate two interleaved phone books by pulling on their spines. In this video, two phone books are interwoven page bypage and the friction between the thin sheets of paper is put to the ultimate test can the frictional force between two interleaved phone books lift a 3, 500 lb car. The hosts of the tv show mythbusters did an experiment once where they interleaved the pages of two phone books.

The fact that the pages of two phone books are interleaved means that friction as well as weight is preventing them from being separated. 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. 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. Rolling friction is the resistance of two objects that are in contact but are then peeled away from each other, such as ripping apart velcro tape or a wheel rolling along the ground. For two books of pages each there are 1999 pagesurfaces in contact. The friction between the pages can be so great that a car can be suspended from such a phonebook pair. There is a friction force red at every point the pages are interleaved. Selfamplification of solid friction in interleaved. So the clamps just bind to the top of each section, the part that does not have the other sides pages interleaved. 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 separate the books. Now well see if you can overcome the friction between the sheets of paper in two books. And then kari, grant and tory test a fishy tale of hollywood pyrotechnics with their own big bang theories.

Can the frictional force between two phone books lift a. People are then invited to pull the directories apart. Friction slows the ball to a stop while preventing your feet some sliding out from under you. Why cant two interleaved phone books be pulled apart.

Mythbusters tried this experiment using interleaved phonebooks. Mythbusters phonebook friction tv episode 2008 imdb. The suggestion that two interleaved phone books cannot be pulled apart is more complex than it seems. This phenomenon is commonly demonstrated with phone books.