Dec 17, 2014 mad scientist, david willey, with the help of his friends ed and kurt, tear apart a pair of interleaved phone books. Selfamplification of solid friction in interleaved assemblies. The experiment was one notebook, the clamping notebook, sat along the. For two books of pages each there are 1999 pagesurfaces in contact. The average normal force between pages then is 12w book.
Key concepts include c friction is a force that opposes motion. The force of friction and the weight of the pages combine, tightly binding the phone books together and making separation impossible for a. A simple alternative to the phone book friction demonstration. Try pulling apart two interleaved phone books and youll inevitably be defeated by huge frictional forces. That just reinforces the importance of testing them. A pair of cars also failed at pulling the phone books apart. A few years ago, an episode of mythbusters explored the strength of interleaved phone books. First you will measure the coefficients of static friction between several combinations of surfaces using a heavy block and a set of hanging masses.
The discovery channels mythbusters recently conducted an experiment to. Phone books are traditionally large but have very thin paper. When you throw a ball up, gravity causes the ball to fall down. Really, friction is a force and should be represented as such.
Mega phonebook car lift power of friction mega live experiment huw. In some instances we used a pulley and weights to find the static and kinetic coefficient of friction and in the last part we inclined the board. This phenomenon is commonly demonstrated with phone books. This friction lab promotes higherlevel inquiry for students. Objective the objective of this experiment is to investigate kinetic friction and drag force.
Using the data from this experiment, the team generated a. Check out this handson activity and see if you can overpower the friction between the books. Physics experimentpresentation on the friction between two phone books where the pages have been interleaved. In this case, you want to measure the angle that the block starts to slide down an incline. Whether you need a classic kids book or classroomproven teaching materials, discover it at scholastic. Put friction to the test with this fun family physics activity. People, trucks and even military tanks have tried and failed the task of pulling apart two phone books lying face up with their pages interleaved, like a shuffled deck of cards. Scientists figure out why interleaved phone books cant be pulled apart. This results in the stack of interleaved pages in the middle being the. The researchers compared this selfinduced friction amplification effect. The mythbusters tried to pull the two phone books apart with human power, which was unsuccessful. Graphs, observations, procedures all of science falls by the wayside without a way of recording the information.
Friction lab data surface mass g incline force n investigating the factors of friction carpet desk book desk desk desk desk desk desk ramp ramp ramp what factors affect static friction. Coefficients of static friction for a few common materials. At frictionlabs, we make clean, efficient chalk for athletes who demand better grip. Selfamplification of solid friction in interleaved assemblies hector alarcon,1,2 thomas salez,2 christophe poulard,1 jeanfrancis bloch,3 elie raphael,2 kari dalnokiveress,2,4 and frederic restagno1. Prelab what is the coefficients of kinetic friction and the coefficient of static friction for the pair of. Because of the way interpenetrating sheets deform, the harder you pull, the greater the friction force resisting separation. Next, you will measure the coefficient of kinetic friction between two. Astonishingly, it turns out to be practically impossible to separate two interleaved phone books by pulling on their spines, however much force is applied. Take two phone books, interleave their sheets, and attempt to separate the. The pages of the sticky note pads are held together by friction. The graph below the action is a graph of the tension in the string.
While it is certainly possible to include numerically an adhoc loaddependent coe cient of kinetic friction, this would be at the cost of simplicity and additional free parameters. Sep 10, 2008 it is impossible to separate two interlocked phone books due to the massive amount of friction between the 800 pages of each book. An inquirybased laboratory on friction vera montalbano department of physical sciences, earth and environment, university of siena, siena, italy abstract date of last change of the paper. Really, it is important to point out that these models dont always work. Do you think the relationship between the number of pages and maximum weight supported is linear, exponential, or something else.
You can see this if you look at your books edgeon while you do the experiment. Visit scholastic, the worlds largest childrens book publisher. 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. Physicists solve the mystery of interleaved phone books. In this lab, you will make some basic measurements of friction. We found out that whenever the normal force of the brick, or with any object increases, the frictional force also increases. The interleaved portions of the post it notes should be free from clamps. The interleaved phonebook demonstration is important because it is just. Conclusion in this lab, my partners and i tried to find out what the relationship between the normal force and frictional force of a brick is. You will be pulling with increasing tension until the object begins to slide and then you will keep the object moving at a slow steady speed. The goal of this lab is to determine the coefficients of friction for a few cases. Even a small number of interleaved pages can result in a surprisingly large amount of friction, making the sticky notes impossible to pull apart. A person sliding a book across a table creates friction.
Can the frictional force between two phone books lift a. A popular science demonstration shows that when you overlap the pages of two phone books, they are nearly impossible to pull apart. Chalk up less, perform at your best and keep your hands healthy and strong. In this lab you will investigate the factors that affect friction. Crooms physics lab 069 friction notebook lab purpose. Learn the physics behind the surprisingly powerful force of friction. Static friction is the force responsible for holding an object in place. Oct 22, 2015 what observations can you make about friction in this process. 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. Researchers explain why its nearly impossible to separate. It is indeed possible to find some case that dont agree with these two models. Kari dalnokiveress, thomas salez, and frederic restagno because of the way interpenetrating sheets deform, the harder you pull, the greater the friction force resisting separation. 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.
Dempster park ridge il 60068 708 8254484 objectives. Physicists solve the mystery of interleaved phone books mit. Scientists figure out why interleaved phone books cant be pulled. Aug 26, 2015 people, trucks and even military tanks have tried and failed the task of pulling apart two phone books lying face up with their pages interleaved, like a shuffled deck of cards. 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. 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. Friction and gravity exist in every aspect of a persons life. Frictionlabs chalk for athletes who demand better grip. We help you find that feeling so you can chalk up less, perform at your best, and keep your hands healthy and strong.
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. 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. In this lab, students will measure coefficients of friction and show that the. Well measure the coefficient of kinetic friction for a wood block sliding on a plane and demonstrate that the friction force is independent of the area of contact and that the force is proportional to the normal force acting on the block. Why cant two interleaved phone books be pulled apart. In this letter, we have instead opted to capture the essential physics needed to elucidate the interleaved. Tearing two interlaced phone books apart using two 18 wheeler trucks. Since most people do not have two phone books sitting around, we will show you how you can do the same experiment with sticky notes. Alarcon and co describe their experiment which measured the force. The friction forcegenerated by the two interleaved.
What are some of the incorrect explanations for the phone book friction experiment. Our lab uses the force of gravity in order to find the maximum static friction force on an object before it turns into kinetic friction. It is nearly impossible to separate two interleaved phone books when held by their spines. For most paper, the coefficient of friction is in the range of 0. When you intertwine two notebooks, page by page, they become inseparable books. Scientists figure out why interleaved phone books cant be. Ellen still isnt convinced the phone book is a waste of paper. People have tried pulling two interleaved phone books apart by playing tugofwar or even attaching them to cars or tanks driving in opposite directions.
Frederic restagno of the university of parissud and cnrs in orsay and his colleagues measured the force needed to separate interleaved pairs of books with between 12 and 100 pages, and they developed a mathematical model based on simple geometric and mechanical. It is impossible to separate two interlocked phone books due to the massive amount of friction between the 800 pages of each book. 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. The force of friction we will be completing a formal lab report on the force of friction you will record a rough draft of the investigation in your science notebook your final draft must be typed, double spaced, and have standard margins due beginning of 2nd quarter exact date tbd. How many pages have to be interleaved before the books resist being pulled apart. Phone book paper is on the rougher side, probably 0. The friction between the pages can be so great that a car can be suspended from such a phonebook pair.
Researchers explain why its nearly impossible to separate two. Phonebooks made of paper have been going out of style, but they are still of interest to physicists. To learn how to measure the coefficient of frictions for various materials to explore the relationship between static and kinetic friction. Now french researchers have performed experiments with smaller booklets and developed a mathematical model that explains why the friction can become so large. Will tory and kari successfully pull apart two phone books in 30 minutes without breaking their teeth. Friction lab friction is a force that occurs when two surfaces touch. It turns out the friction comes from the shape of the phone book and how pulling affects it. Sep 22, 2009 homework statement we recently performed an experiment to determine the static and kinetic coefficients of friction by moving a box along a board. A famous demonstration of the counterintuitive power of friction involves two. A remarkable demonstration of the influence of friction involves a pair of phonebooks with their pages interleaved. Tearing two interlaced phone books apart using two 18 wheeler. First, some context, in case you are a child of the 21st century, and so perhaps have no personal experience with paper telephone. The goal of this lab is to explore two models for the frictional force.
Mar 11, 2020 the interleaved portions of the post it notes should be free from clamps. 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. It turns out the friction comes from the shape of the. When a few pages are interleaved, you may find the books pull apart easily. 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. Phone book friction science activity at science buddies. The humble phone book has been the subject of one of the. Friction force lab friction forces lab finding an objects through the use of tension force victor jeung, cathy liu, jason feng, terry tong 2011 october 14. Explore friction by launching stuff, from scientific.
But the results change as you interleave more and more pages. For example, almost every movement you make, such as walking and running, involves friction. The factors being tested will include the effect of surface texture, weight and surface area contact on friction. Why cant you separate interleaved books physics today.
Aug 17, 2015 physicists solve the mystery of interleaved phone books. Also see the sequel in mythbusters, or maybe even try it yourself. Its well known that two phone books with their pages interleaved are. 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. You will measure frictional forces using a spring scale to measure the force. The fact that the pages of two phone books are interleaved means that friction as well as weight is preventing them from being separated. Whether youre a brand new climber or a seasoned pro, you crave the moment where your grip does more than you thought it could. Feb 16, 2008 in relation to this interleaved phone book the normal force is applied to all the pages in series instead of in parallel.
Pulling apart two interleaved phone books physics stack exchange. It is an old barroom trickmaking a nexttoimpossible task seem easy. At frictionlabs we make clean, longer lasting chalk for athletes who demand better grip. 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. Why can two phone books with interleaved pages support so much weight. Try pulling apart two interleaved phone books and youll inevitably be.
The suggestion that two interleaved phone books cannot be pulled apart is more complex than it seems. Inseparable books experiments steve spangler science. In order for an object to move, the applied force must overcome the force of static friction. In this weeks family science activity, families explore properties related to friction by experimenting with phone books or even pads of paper. To investigate the drag force, we will measure the terminal. The fact that the pages of two phone books are interleaved means that friction as. Phone book friction, from mythbusters the enigma of the two interleaved phonebooks pdf, from cornell university library slippery science. Friction lab strand force, motion, and energy topic investigating motion primary sol 4. This lab will let you determine the coefficients of static friction and kinetic friction between different surfaces.