This net force will cause an acceleration opposite the direction of motion. Scientists figure out why interleaved phone books cant be. For two books of pages each there are 1999 pagesurfaces in contact. The suggestion that two interleaved phone books cannot be pulled apart is more complex than it seems. When one vector is opposite another, one of the two needs to be negative. Its well known that two phone books with their pages interleaved are almost.
No, its cleveland state university physics professor jearl walker performing a daring phone book stunt. Why it takes tanks to separate two phone books the pipettepen. Take the above myth busters clip for example, when the friction in between the sheets of a phone book in between the pages of a second phone book make them extremely difficult to separate. Jan 15, 2016 the friction created by the pulling and the angle of the pages keeps the books interlocked and inseparable.
Phone book friction blog alphageek aplusphysics community. Some folks insist that there is no friction involved in electricity. Physicists solve the mystery of interleaved phone books mit. Why cant two interleaved phone books be pulled apart. Will tory and kari successfully pull apart two phone books in 30 minutes without breaking their teeth.
Physics study guides this note describes the following topics. Shuffle two phone books together like a deck of cards. Friction slows the ball to a stop while preventing your feet some sliding out from under you. If there is little to none, that ball will keep rolling, and rolling, and rolling. Popular friction books meet your next favorite book. Anyway, who could explain the facts with this dilemma. The mythbusters arent really doing it wrong, but they give me a chance to talk about some physics. It puts an emphasis on the microscopic mechanisms underlying the phenomenon of friction. The friction created by the pulling and the angle of the pages keeps the books interlocked and inseparable. Aparently if you put 2 phone books page on page untill you reach the end then put two cars to pull the phone books apart the phone books wont rip or come apart because of friction is this true. Coefficients of static friction for a few common materials. The fact that the pages of two phone books are interleaved means that friction as well as weight is preventing them from being separated. Learn the physics behind the surprisingly powerful force of friction. For more physical entertainment visit the flying circus of physics on youtube.
This section contains free ebooks and guides on physics, some of the resources in this section can be viewed online and some of them can be downloadable. Inseparable books experiments steve spangler science. Aparently if you put 2 phone books page on page untill you reach the end then put two cars to pull the phone books apart the phone books wont rip or come apart because of friction is. The force of friction and the weight of the pages combine, tightly binding the phone books together and making separation impossible for a. Researchers explain why its nearly impossible to separate.
Try pulling apart two interleaved phone books and youll inevitably be defeated by huge frictional forces. Two equalsize books does not have to be a phone book or two thick magazines, notepads or tablets. Static friction is directly proportional to the normal force, and it increases until the object begins to move. Smartphone physics in the park to explore the power of your phone, heres a simple physics experiment you can do at your local park. To help during this pandemic, ive lowered the price of my membership which has over digital resources plus over a 100 flipped video lessons you can provide your students with so they dont fall behind. A wheel turns because of its encounter with the surface of the road. Put friction to the test with this fun family physics activity. This is exactly what the team investigating the friction of phone books. Finally, phone book paper is amongst the cheapest of papers. In the equation t2 t1e, we have t2 50 kg, t1 40 kg, and. The study of sliding friction is one of the oldest problems in physics, and certainly one of the most important from a practical point of view. In this weeks family science activity, families explore properties related to friction by experimenting with phone books or even pads of paper. 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.
The convenient thing to do for this problem is to let friction be the negative one. Practice finding the acceleration of an object when static and kinetic friction forces are included. View homework help phone book friction presentation. What is the friction force holding two of these interlaced phone books together. Physicists solve the mystery of interleaved phone books. 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. Table 1 shows the static friction coefficients for some common materials. Phone book friction science activity at science buddies phone book friction science activity at scientific american making connections. Friction is result of the irregularities on the two surfaces in contact of each other. 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. Lowfriction surfaces are in increasingly high demand for hightech components such as computer storage systems, miniature motors, and. While physicists have long known that this must be due to enormous frictional. 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.
The force in question is the friction between individual sheets amplified by the huge number of pages in each directory. A famous demonstration of the counterintuitive power of friction involves two telephone directories with their pages alternately interleaved. In short, it is extremely difficult to pull apart two phone books whose. Rubbing two sticks together produces heat and light. Kinetic friction is a constant, and it is less than or sometimes nearly equal to the maximum static friction. The backoftheenvelope answer is friction between the pages. 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.
Friction eats up energy you would normally convert into useful energy. The da vinci code by dan brown, pride and prejudice by jane austen, friction by sandra brown, half girlfriend by chetan bhagat. Phone book friction justin lazaro, tarissa miller, john biehle. Of course, friction only occurs when two surfaces are pushed together, and. Physics forces friction adam and jamie have bound two phone books together by interleaving their pages. Low friction surfaces are in increasingly high demand for hightech components such as computer storage systems, miniature motors, and aerospace devices. Mythbusters phone book friction worksheet season 6. 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. Correction to force of friction keeping the block stationary. Each page in contact has the friction caused by the weight of the pages above it pushing down. Abstract 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. Simply by swinging on a swing and collecting a bit of data, you can measure the length of the swing without ever pulling out a ruler. Today, i am excited to share one big, fantastic nugget from the book the idea of friction. This book is an excellent introduction to the physics of sliding friction.
Kinematics and dynamics, units and vectors, motion in one dimension, motion in two and three dimensions, forces, work and energy, linear momentum and collisions rotations, vibrations and waves, rolling motion, oscillatory motion, electric fields, electric charge and coulombs law. The classical description of a particle, hilbert space formalism, group theory, lie algebra, the green function approach, the. In their update of the snowplow split myth, tory, grant and kari unleash 12 rockets and 75,000 pounds of thrust on an unsuspecting car. This makes the normal force and hence friction increase with increased tension. To pull the boards apart the friction force between the boards, plus the shear strength of the bolts, must be exceeded. Once the forklift stops pushing, kinetic friction becomes the net force. 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. It is an old barroom trickmaking a nexttoimpossible task seem easy. For other handson science projects related to this exploration of friction, see the following. Interesting quote guillaume amontons 16631705 france. Friction is the force that opposes motion when two surfaces are in contact. 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 humble phone book has been the subject of one of the more entertaining physics puzzles in recent years. Phone book friction against army tanks mythbusters, 20080918 will phone books lift a 1600 kg car. When tempers flare during a particularly complicated myth, jamie offers up a simple solution. Friction in a light bulb my wife and i are having a friendly dispute over the cost of operating electric light bulbs. Fermilab science inquiring minds questions about physics. A simple alternative to the phone book friction demonstration. The more pages you put together, the bigger the area and the more friction you create. This phenomenon is commonly demonstrated with phone books. Phone book paper is on the rougher side, probably 0. 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. People have tried pulling two interleaved phone books apart by playing tug. It puts an emphasis on the microscopic mechanisms underlying the phenomenon. If youre seeing this message, it means were having trouble loading external resources on our website. A simple alternative to the phone book friction demonstration article in the physics teacher 566.
Free physics books download ebooks online textbooks tutorials. It is not made to last long, and it is not particularly wellmade. Test which surfaces create more friction, see how strong friction is, learn how to reduce friction, and even discover the side effects of friction. Free physics books download ebooks online textbooks. The phone books wouldnt come apart using all the mythbusters gadgets and even attaching the phone books between two cars. Even a small number of interleaved pages can result in a surprisingly large amount of friction, making the sticky notes impossible to pull apart. Take two phone books and lie them face up, with the spines facing away from. Explore the physics of friction using sticky notes. Challenging the widespread view that globalization invariably signifies a clash of cultures, anthropologist anna tsing here. They attempt to pull the two phone books apart and measure how much force it takes to do so. As it turns out, though squarely in the domain of classical physics, the phone book. May 07, 2009 mythbusters phone book friction discovery. Find out jamies idea of a great name for a baby, as well as his preferred title for a romance novel should he write one. When the force of friction covers a big area, it becomes very strong.
Phone books are traditionally large but have very thin. Phonebook friction against army tanks mythbusters, 20080918 will phone books lift a 1600 kg car. 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. Intuition on static and kinetic friction comparisons.
Believe it or not, this commonly viewed as weak force can add up. Oct 22, 2015 put friction to the test with this fun family physics activity. After all, youre pulling on the spines of the books and friction directly. May 01, 2008 when the force of friction covers a big area, it becomes very strong.
Phone book paper is not uniform, from sheet to sheet, and even within a sheet. The pages of the sticky note pads are held together by friction. Aug 17, 2015 physicists solve the mystery of interleaved phone books. If theres too much friction, that ball wont roll for very long. 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 separate the books. People are then invited to pull the directories apart. In both cases, it is friction that produces movement, action, effect. Therefore the maximum pull force must be below the force needed to do this.
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