Feb 16, 2008 if each phone book is 500 pages, then when you interleave them you are putting pages on top of each other. Mythbusters phone book friction video february 19, 2017. Shuffle two phone books together like a deck of cards. 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. In this episode they tried to bust the myth that it is impossible to pull two interleaved phone books apart. We consider a factor that has not been part of the popular explanation atmospheric pressure.
Tektronix has developed the asynchronous time interleave ati bandwidthmultiplication technology used in the 70ghz model dp070000sx. The mythbusters tried to pull the two phone books apart with human power, which was unsuccessful. The energy lost to friction is turned into sound and heat. 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. Physics the strength of interleaved phonebooks explained. Mythbusters phone book friction video this is a short video clip from the episode of mythbusters on the discovery channel. Phone book friction science activity at science buddies phone book friction science activity at scientific american making connections. The force of friction and the weight of the pages combine, tightly binding the phone books together and. So the clamps just bind to the top of each section, the part that does not have the other sides pages interleaved.
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. Handbook of frictionvibration interactions introduces the principles and provides the resources to understand and work with them. The trick apparently also works pretty well with reasonably thick magazines. But the results change as you interleave more and more pages. Overlap the pages of the phone book together, flipping pages over one another. Physicists solve the mystery of interleaved phone books mit. 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. 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. A long time ago, a phone book was a book that had an index of phone numbers for everyone in your city. A remarkable demonstration of the influence of friction involves a pair of phonebooks with their pages interleaved. Interleave article about interleave by the free dictionary. A pair of cars also failed at pulling the phone books apart. When you pull on the phone books, the pages want to straighten out to be in the direction of the force. Friction topics, including static or limiting friction, kinetic, dynamic or sliding friction, coefficient of static and kinetic friction.
In short, it is extremely difficult to pull apart two phone books whose pages have been interleaved. Each page in contact has the friction caused by the weight of the pages above it pushing down. There is a friction force red at every point the pages are interleaved. The tv show mythbusters had an episode in which they interleaved two phone books and dramatized how hard it was to pull them apart. Physics experimentpresentation on the friction between two phone books where the pages have been interleaved. The force of friction equation is actually three equations is one. Phone book physics by mcmaster university mythbuster fans have likely heard of the phenomenon of interlocking pages of two phonebooks and discovering that they are impossible to pull apart. First, some context, in case you are a child of the 21st century, and so perhaps have no personal experience with paper telephone. In a powder, the friction that is developed by the particles sliding over each other. 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. Phone book paper is on the rougher side, probably 0. A unified theoretical framework includes some of the most important engineering applications.
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 fact that the pages of two phone books are interleaved means that friction as well as weight. For example, almost every movement you make, such as walking and running, involves friction. Friction is due to a normal force, meaning that the direction in which. Despite his best efforts, the friction between all of the pages prevents him from separating the. Will tory and kari successfully pull apart two phone books in 30 minutes without breaking their teeth. Friction is the force that opposes motion when two surfaces are in contact. The suggestion that two interleaved phone books cannot be pulled apart is more complex than it seems. Why cant you separate interleaved books physics today. Feb 19, 2017 mythbusters phone book friction video this is a short video clip from the episode of mythbusters on the discovery channel. 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 person sliding a book across a table creates friction.
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. Friction is a force that acts to stop the movement of two touching things. When a few pages are interleaved, you may find the books pull apart easily. It is an old barroom trickmaking a nexttoimpossible task seem easy. Graphs, observations, procedures all of science falls by the wayside without a way of recording the information. It is impossible to separate two interlocked phone books due to the massive amount of friction between the 800 pages of each book. Clearly, such works reveal drastic departures from the simple ac laws, as one approaches the nanoscale. Mega phonebook car lift power of friction mega live experiment huw james head squeeze duration. See more ideas about force and motion, physical science and science experiments.
A few years ago, an episode of mythbusters explored the strength of interleaved phone books. Now attempt to pull the books apart by their spines. Explore friction by launching stuff, from scientific. Why cant two interleaved phone books be pulled apart. 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. Selfamplification of solid friction in interleaved assemblies.
Explanation friction is a kind of force that occurs between surfaces against the motion or tendency to move robertson 2014. In relation to this interleaved phone book the normal force is applied to all the pages in series instead of in parallel. Also see the sequel in mythbusters, or maybe even try it yourself. Yes it does, because when the pull is harder, the speed is faster, so the force is increasing, therefore the sliding friction is bigger. Notebooks are a necessity in every science setting. Take two phone books and lie them face up, with the spines facing away from each other. Tearing two interlaced phone books apart using two 18 wheeler trucks duration. Oct 22, 2015 put friction to the test with this fun family physics activity. This is exactly what the team investigating the friction of phone books did. For a more thorough explanation and a list of common misconceptions, see the project idea can you lift a car with two phone books. Phonebooks made of paper have been going out of style, but they are still of interest to physicists.
In the beginning of the class every single student voted that it. Inseparable books experiments steve spangler science. Friction action force friction the friction force acts in a direction parallel to the area of contact, and opposes the motion or the tendency to move. The suggestion that two interleaved phone books cannot be pulled apart is more. Phone book physics by mcmaster university mythbuster fans have likely heard of the phenomenon of interlocking pages of two phonebooks and discovering that they are impossible to. Friction simple english wikipedia, the free encyclopedia. May 28, 2012 friction is a key phenomenon in applied physics, whose origin has been studied for centuries. We took a poll at the beginning of our class on whether pages of a phone book interleaved like the post it notes could lift a human, or amybe a car. Friction slows the ball to a stop while preventing your feet some sliding out from under you.
If each phone book is 500 pages, then when you interleave them you are putting pages on top of each other. 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. Phone books are traditionally large but have very thin paper. Physicists solve the mystery of interleaved phone books. The simple explanation often given is t hat gravity provides. Until now, it has been understood that mechanical wearresistance and fluid lubrication affect. Researchers explain why its nearly impossible to separate. Now french researchers have performed experiments with smaller booklets and developed a mathematical model that explains why the friction can become so large.
Coefficient of friction definition is the ratio of the tangential force that is needed to start or to maintain uniform relative motion between two contacting surfaces to the perpendicular force holding them in contact, the ratio usually being larger for starting than for moving friction. Moreover, friction can be further complicated by a stickslip response, as seen in many cases 16, 17. Friction makes two notebooks, intertwined by their pages, impossible to pull apart. Researchers explain why its nearly impossible to separate two interleaved phonebooks.
Despite his best efforts, the friction between all of. Friction is a key phenomenon in applied physics, whose origin has been studied for centuries. Handbook of frictionvibration interactions 1st edition. 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. Mar 11, 2020 the interleaved portions of the post it notes should be free from clamps. Coefficients of static friction for a few common materials. The more pages you add, the larger this effect becomes. In this article we consider the wellknown demonstration of friction by two interleaved books. Then interleave the pages and try to pull the books apart. The introductions were written on scotts usual writing paper, but the notes were written on interleaves blank sheets of paper inserted between the leaves of his printed novels. Supposing that the static coefficient of friction between the pages is the same as that between a book and a table, than in this case the friction force between the books equals 1 1999.
The ratio mentioned above is called coulombs law of friction coulomb was a french physicist, 17261806. The interleaved phonebook demonstration is important because it is. 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. The first three chapters in the book introduce basic concepts and analytical methods of friction and vibration. The backoftheenvelope answer is friction between the pages. Why it takes tanks to separate two phone books the pipettepen. Although the friction coefficient does not have a measurement unit force divided by force, the law can be easily checked. For other handson science projects related to this exploration of friction, see the following. As cited in darling 2012, the myth busters tv series developed a demonstration to show how strong the force of friction can be. In this weeks family science activity, families explore properties related to friction by experimenting with phone books or even pads of paper. This type of braid is applicable to sutures in surgery 30, and is also thought to play a role in adhesive proteins 31.
Phone book friction, from mythbusters the enigma of the two interleaved phonebooks pdf, from cornell university library slippery science. Gravity is simply defined as what goes up must come down. 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. 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. Learn the physics behind the surprisingly powerful force of friction. Rn the friction force does not depend on the surface area. This results in a huge increase in the friction force, making them nearly impossible to pull apart. Table 1 shows the static friction coefficients for some common materials.
For two books of pages each there are 1999 pagesurfaces in contact. It would probably generate many student questions that could lead into the explanation of friction. Dec 09, 2015 researchers explain why its nearly impossible to separate two interleaved phonebooks. The friction between the pages can be so great that a car can be suspended from such a phonebook pair. Static friction is when the friction is strong enough to stop movement between two objects. Researchers explain why its nearly impossible to separate two. Houde gives his best effort to pull to books apart that have their pages interleaved together. Test which surfaces create more friction, see how strong friction is, learn how to reduce friction, and even discover the side effects of friction. Oct 22, 2015 phone book friction, from mythbusters the enigma of the two interleaved phonebooks pdf, from cornell university library slippery science. We provide three control experiments to demonstrate the role of atmospheric pressure in the twobook experiment and an additional simple demonstration of. Coefficient of friction definition of coefficient of. Separating books experiment try pulling apart two interleaved books duration. Does the dragging speed have any effect on the coefficient of sliding friction, usliding.
Friction is a force science experiment science experiments. Friction and gravity exist in every aspect of a persons life. Internal friction article about internal friction by the. One by one interleave the pages of the two books by folding down a page. Paper related content,qvhsdudeohskrqherrnvghprqvwudwlrq. May 12, 2016 mega phonebook car lift power of friction mega live experiment huw james head squeeze duration.
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