Presentation Transcript

1. Man Power against Paper Friction

   Chris Valdez Lavelle Blackwater Sarah Miller
2. Friction 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.
3. Friction In a Phone Book 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.
4. 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.)
5. Free-Body Diagram To Find Friction Fy = FN - mgcos = 0 Fx = mgsinf = 0 mgsin - FN = 0 mgsin - mgcos = 0  = tan
6. Finding Static Friction s of Paper fs = smgcos 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 = 35º fs = 0.53*0.01 lbs*cos(35º) = 4.34 x 10-3 lbs on any page
7. Finding Kinetic Friction k of Paper fk = kmgcos 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 = 25º fk= 0.47*0.01 lbs*cos(25º) = 3.21 x 10-3 lbs on any page
8. Data of the Pages 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: FN = (# of pages in phone book)*mg Force applied to each page: F = (# of pages in phone book)*smg
9. Data of the Pages Example: Number of pages: 600 Weight of the Phone book: 6.00 lbs Weight of one page: 0.01 lbs FN = mg = 6.0 lbs on each page fs = µSFN = 0.81*6.0 lbs on each page = 4.9 lbs Total Friction = 4.9 lbs/page * 600pages = 2916 lbs
10. Need to Know 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.
11. Finding the Total Force of Friction Ff = smg Fft = 2Ff x npages µS = .81 Weight of book mg = 1.48 lbs Pulling the phone books apart Fft = 2(smg) x 2npages Fft = 2(0.81 x 1.48 lbs) x 2(591) Fft = 2837 lbs
12. How Many People Does it Take to Pull Two Phone Books Appart? 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).
13. Works Cited 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