Tippens, professor of physics southern polytechnic state university a powerpoint presentation by. I bought this book for my 8th grade students who do not understand friction, and had to be retested on it. Sep 26, 2015 one of the sessions focuses on different types of friction. Can a shark be blown up like they did in deep blue sea. Physics describes how electricity interacts with the various circuits. Adhesion varies with substances in contact and is a complicated aspect of surface physics. The two given in tables and problems are just for the two nontransitional states. 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 am. 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. 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.
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. Ellen still isnt convinced the phone book is a waste. A mobile phone is pulled northward by a force of 10 n and at. Students are asked to solve problems with newtons second law and apply their knowledge of friction to the problem solving process. Pulling apart two interleaved phone books stack exchange. Find out whether jamie hyneman and adam savages ducttape canoe can survive waves 3 to 4 feet taller than their bow, and see what. Will tory and kari successfully pull apart two phone books in 30 minutes without breaking their teeth. Are two interlaced phone books impossible to pull apart by any means. By the end of this unit students should be able to describe several types of friction. Students will use the coefficient of friction either static or kinetic and the normal force.
Scientists figure out why interleaved phone books cant be. Whenever two human beings spend time together, sooner or later they will probably irritate one another. Frictional force on car tyres friction is the force that opposes the motion of an object as it moves. 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. View homework help phone book friction presentation.
Explore the physics of friction using sticky notes. Until now in physics, youve probably been ignoring friction to make things simpler. Learn the physics behind the surprisingly powerful force of friction. Friction accounts for how your feet move across grass, for example, compared to how an ice skate moves across ice. Phonebook friction against army tanks mythbusters, 20080918 will phone books lift a 1600 kg car. This video tutorial helps explain the basics of friction. Mythbusters phone book friction full episode video.
Then, a 30 n 30\,\text n 3 0 n 30, start text, n, end text horizontal force. We are also given based from the discussion of the college physics book that t25,900 newtons. A 10kg brick and a 1kg book are dropped in a vacuum. Test which surfaces create more friction, see how strong friction is, learn how to reduce friction, and even discover the side effects of friction. Feb 19, 2017 mythbusters phone book friction video this is a short video clip from the episode of mythbusters on the discovery channel. Friction is the force that resists the motion of one surface relative to another with which it is in contact. A long time ago, a phone book was a book that had an index of ph. 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. In fact, almost everything around you can be described quite accurately by the laws of physics.
The combined weight of pages a, e, b, f, c is 5w so the friction force between c and g is 5w s. Its well known that two phone books with their pages interleaved are almost. Finally, phone book paper is amongst the cheapest of papers. Physicists solve the mystery of interleaved phone books. Today, i am excited to share one big, fantastic nugget from the book the idea of friction.
Why is the normal force not divided for every friction plate since there are multiple point of contacts. Phone book friction blog alphageek aplusphysics community. Physics teachers spend their days showing and explaining the marvels of physics, which underlies all the other science subjects, including biology, chemistry, earth. For example, page one of the first phone book should overlap page one of the. 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.
As a member, youll also get unlimited access to over 79,000 lessons in math, english, science, history, and more. The humble phone book has been the subject of one of the more entertaining physics puzzles in recent years. You will find friction everywhere that objects come into contact with each other. Take two phone books and lie them face up, with the spines facing away from. Now, its time to include this very real force and see what happens. For two books of pages each there are 1999 pagesurfaces in contact. Lowfriction surfaces are in increasingly high demand for hightech components such as computer storage systems, miniature motors, and aerospace devices. The harder you pull, the greater the force of friction. Physics aims to describe the function of everything around us, from the movement of tiny charged particles to the motion of people, cars, and spaceships. For the simple example of a book resting on a flat table, the frictional force is zero. Phone book paper is not uniform, from sheet to sheet, and even within a sheet. Demonstrating the power of friction with phonebooks. But you have to post basic things in biology,physics. The force in question is the friction between individual sheets amplified by the.
Their assignment was to read this childrens book to each other and discuss it, page by page, while looking at the pictures. The mythbusters tried to pull the two phone books apart with human power, which was unsuccessful. Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Important questions for cbse class 11 physics chapter 4. 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. Shuffle two phone books together like a deck of cards. Two equalsize books does not have to be a phone book or two thick magazines, notepads or tablets. 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. 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.
Demonstrating the power of friction with phonebooks youtube. I thought that in the phone book example, the normal foce acts through multiple surface areas, so the total normal force through all the surface areas n x normal force. There arent just two coefficients of friction, its a continuum. See the bibliography and search the internet for phone book friction and you will find plenty of videos showing the experiment. Phone book friction justin lazaro, tarissa miller, john biehle. 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.
Friction basics friction is a force that holds back the movement of a sliding object. According to legend, if you interweave the pages of two phone books it is nearly impossible to pull them. They then compared and contrasted the contents of this book with the section of their textbook that discussed. Physicist kari dalnokiveress did his own interleaved phone book mythbuster experiment and recruited students to help him. This is the standard graph of the coefficient of friction vs the force perpendicular to the surfaces that shows up in most elementary physics textbooks.
Physics is that branch of science which deals with the motion and types of energies of matters around us, types of energies include heat energy, kinetic energy work energy, etc. 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. One of the sessions focuses on different types of friction. The magnitude of the acceleration depends on two forcesthe thrust and the friction. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Physicists solve the mystery of interleaved phone books mit. We can state that the net force is equal to thrust minus friction. To test how much force is needed to overcome static friction, you can try dragging a shoe over various surfaces. Discuss friction and find out if it is good or bad giving typical examples. While physicists have long known that this must be due to enormous.
Measure how far the rubber band had to stretch in order for the shoe to move. Tug on the other end of the rubber band until the shoe starts moving. Find out whether jamie hyneman and adam savages ducttape canoe can survive waves 3 to 4 feet taller than their bow, and see what made adam cry, uh oh. Free pdf download of important questions with solutions for cbse class 11 physics chapter 4 motion in a plane prepared by expert physics teachers from latest edition of cbsencert books. Overlap the pages of the phone book together, flipping pages over one another. The acceleration of one of four rockets burning newtons. Apr 15, 2015 are two interlaced phone books impossible to pull apart by any means. The force acts in the opposite direction to the way an object wants to slide. A simple alternative to the phone book friction demonstration. Based from newtons second law of motion, we can calculate for the acceleration as.
The combined weight of pages a, e, b, f is 4w so the friction force between c and f is 4w s. The friction between two objects determines how difficult it will be to slide one object across another. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. It is not made to last long, and it is not particularly wellmade. The hints and answers for these friction problems will be given next. In the process i revived the conundrum of phone book friction. That static friction sliding friction is important in antilock breaking systems in cars see your book for more on this. Part of the friction is due to adhesive forces between the surface molecules of the two objects, which explain the dependence of friction on the nature of the substances. The force in question is the friction between individual sheets amplified by the huge number of pages in each directory. Friction and equilibrium a powerpoint presentation by paul e. Plan how you would reduce friction between the desk and the floor. For example, if you are using a lightweight testing rig, you could decide to test 2, 4, 6, 8, 10, and 12 pages per stack of sticky notes so 4, 8, 12, 16, 20, and 24 pages total when they are interleaved.
The friction created by the pulling and the angle of the pages keeps the books interlocked and inseparable. Friction plays a crucial role in the development of roller skates as well as the means with which you choose to stop. Intuition on static and kinetic friction comparisons video. If theres too much friction, that ball wont roll for very long. The combined weight of pages a, e, b, f, c, g is 6w so the friction force between d and g is 6w s. The new model allows all these forces to be calculated for the first time. Dry friction resists relative lateral motion of two solid surfaces in contact.
Each page in contact has the friction caused by the weight of the pages above it pushing down. Believe it or not, this commonly viewed as weak force can add up. 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. If a car needs to stop at a stop sign, it slows because of. This makes the normal force and hence friction increase with increased tension. Low friction surfaces are in increasingly high demand for hightech components such as computer storage systems, miniature motors, and aerospace devices. 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. The backoftheenvelope answer is friction between the pages. 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. See the bibliography and search the internet for phone book friction and you will find. Of course, friction only occurs when two surfaces are pushed together, and experimenters often explain that gravity is the force that pushes the pages together in these experiments.
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