Chris Valdez
Lavelle Blackwater
Sarah Miller

 Do you believe that is is possible for one person to pull two (Phoenix - Metro Area) phone books apart? Ten people? Thirty people?
 For the above questions that answer is no, it takes a greater amount of force to pull the two phone books apart.

For this phone book pull experiment the phone book that was used was a Phoenix-Metro Area phone book. This type of phone book has significantly more pages than other phone books that can be used. In the explanation of how much friction an individual phone book can have there will also be another example (a
GCC course guide) with similar page types.

A phone book has both static and kinetic friction.
 Static friction: this is the force that is formed from the overlaying of each page on top of each other. (The friction that must be broke to move the object from its resting point.)
 Kinetic friction: this is the force from the movement of the pages. (The force that opposes the applied force to the motion of an object.)


F y

F x
= F
N
- mgcos

= 0
= mgsin
 f = 0 mgsin


= tan

-

F
N
= 0 mgsin

-
 mgcos

= 0
QuickTime™ and a
decompressor are needed to see this picture.


 s f s
=  s mgcos 



Example (theoretical data used):
Assume phone is 6 lbs and 600 pages.
Mg /page is 0.010 lbs mg = 0.01 lbs
 s
= 0.53

= 35
º f s
= 0.53*0.01 lbs*cos(35 º ) = 4.34 x 10 -3 lbs on any page


 k f k
=  k mgcos 
 Example (theoretical data used):
Assume phone is 6 lbs and 600 pages.
Mg /page is 0.010 lbs mg = 0.01 lbs
 k
= 0.47

= 25
º f k
= 0.47*0.01 lbs*cos(25 º ) = 3.21 x 10 -3 lbs on any page





Mass of each page is approximately .21g or 2.1 x 10 -4 kg.
Weight of each page is approximately .002N or 2.0x10
-3 N.
Normal force equation of each individual page:
F
N
= (# of pages in phone book)*mg
Force applied to each page:
F = (# of pages in phone book)*  s mg

Example:
Number of pages: 600
Weight of the Phone book: 6.00 lbs
Weight of one page: 0.01 lbs f
F
N s
= mg = 6.0 lbs on each page
= µ
S
F
N
= 0.81*6.0 lbs on each page = 4.9 lbs
Total Friction = 4.9 lbs/page * 600pages = 2916 lbs




The force on each page of the phone book has the force of the total weight of the book acting on it. Middle pages only feel the force of one phone book. Pages on the outside of the phone book feel more weight than that of the internal pages.
The force of friction is doubled because of the sandwiching of each page.
When the phone books is then pulled the full force of gravity acts on them.





F f
F ft
=  s mg
= 2F f x n pages
µ
S
= .81 Weight of book mg = 1.48 lbs
Pulling the phone books apart
F
F ft ft
F ft
= 2(  s mg) x 2n pages
= 2(0.81 x 1.48 lbs) x 2(591)
= 2837 lbs



The force to pull two phone books apart is 2837 lbs =12.6 kN.
Maximum value of force a human can push with both hands, no other forces only shoulders and arm strength, 254N = 57.0 lbs.
 Now we can conclude that…
Number of people = 2837 lbs/57.0 lbs = 49.5
So about 50 people can pull a phone book. The number of people will also very depending on the number of pages the phone book has (creating more friction).

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 http://ffden-2.phys.uaf.edu/211_fall2004.web.dir/Jeff_Levison/Freebody%20diagram.htm
http://hereandthere.us/index.php/2012/phone-book-listings/ http://msis.jsc.nasa.gov/sections/section04.htm
http://www.concurringopinions.com/archives/2007/02/are_big_search.html
http://www.apartmenttherapy.com/death-becomes-the-phone-book-164109 http://www.alternative-energy-resources.net/friction_and_lubrication.html