PJ 2 Ward & Mistry 1
Friction Phonebook Experiment
Grade level: Grade 3
Strand: Understanding Matter and Energy
Topic: Forces Causing Movement
Expectations:
 Investigate forces that cause an object to start moving, stop moving, or change direction.
 Conduct investigations to determine the effects of increasing or decreasing the amount of force
applied to an object.
Materials Needed:
 Two phone books (same size)
 Patience!
Description of Procedure:
Step 1
 Ask students what they know about phone books, how big they are, how thick the pages are and
what would happen if we interwove all the of the pages together and pulled in opposite
directions?
Step 2
 Overlap the pages of a phone book page by page. For example, Page 1 of Book 1 goes on top
of Page 1 of Book 2, and then Page 2 of Book 2 goes on top of Page 1 of Book 1 and continues
until all pages are overlapped.
Step 3
 Once the books are completely intertwined, one person grasps the bound edge of one book and
another grasps the bound edge of the other book and they pull in opposite directions.
Step 4
 Have students discuss what observations they made and what conclusions they can draw from
the experiment. Ask students if the experiment would have had a different result if we changed
some of the parameters. For example, glossy pages, fewer pages interwoven, smaller pages etc.
Modify this task by drilling three holes, a half-inch in diameter, on the binding of one of the books.
Weave a strong rope through the holes and tie it securely, leaving about six to eight feet extending off it
perpendicular to the long edge of the book. Repeat this procedure with the other phone book. Direct the
students to pull on the ropes like a tug-of-war game. Increase the numbers of people pulling on the
rope. Discuss the results.
PJ 2 Ward & Mistry 2
Scientific Exploration:
In basic terms, each page of the phonebook has friction against a page above and below it. Since the
pages are rough under a microscope, friction is created and it was nearly impossible to pull the two
books apart by hand.
Friction for elementary students starts with the basics. Friction is a push, pull, or a force which works
against the motion of objects that are in contact as they move past each other. When objects are
touching their surfaces tend to stick together, like the tiny loops and hooks of Velcro. Try to slide your
hands across your desktop or any tabletop. The force you fell which seems to move opposite your hand
is called friction. Heat and sound are also produced by friction. If you rub the palms of your hands
together quickly your hands get warm and you can hear the sound that friction creates.
Without friction life as we know it would not exist. Every surface would be more slippery than ice.
You could not walk, run, write, or even feed yourself without friction. Friction for children is as easy as
using common examples to guide your explanation.
Friction between two rough surfaces is greater than between two smooth surfaces. It also increases as
the size of the contacting surface area increases. There are many ways to test these facts using everyday
objects such as carpeting, smooth floors, sand paper or the smooth top of a desk. Another object that
can be used is the phone book.
Key Terms:
Friction: the force that opposes the motion between the surfaces of two bodies that are in contact.
Friction arises because no surface is perfectly smooth. Some surface may look very smooth, but when
under a microscope, they are still rough.
References:
Friction for Children: 4 Tricks to Help Children Understand Friction
 http://www.articlesbase.com/k-12-education-articles/friction-for-children-4-tricks-to-helpchildren-understand-friction-1416598.html
Friction
 http://www.historyforkids.org/scienceforkids/physics/machines/friction.htm
Friction Phonebook (Myth Busters)
 http://mythbustersresults.com/episode-106-phone-book-friction
Friction Phonebook Video (YouTube)
 http://www.youtube.com/watch?v=hOt-D_ee-JE
By: Dave Ward and Raj Mistry (PJ 2)