The TV show Mythbusters had an episode in which they interleaved two phone books and dramatized how hard it was to pull them apart. (A long time ago, a phone book was a book that had an index of phone numbers for everyone in your city. The trick apparently also works pretty well with reasonably thick magazines.) They ended up needing two tanks to pull the phone books apart against the resistance of friction:
http://www.youtube.com/watch?v=AX_lCOjLCTo
http://www.youtube.com/watch?v=QMW_uYWwHWQ
When one of my students described this in class, it strongly violated my carefully cultivated intuition about friction, and I thought maybe the student was getting the description wrong. Actually it seems right.
Why does this work? I found the following online discussion from 2008, the same year in which the episode aired:
http://www.physicsforums.com/showthread.php?t=215857
Posts 8, 27, and 36 seem the most relevant. 36 quotes the result of a calculation, without saying what the calculation was.
Can anyone give a good analysis?
No comments:
Post a Comment