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Paris, 16 December 2015

Lifting a car with two phone books

Astonishingly, it turns out to be practically impossible to separate two interleaved phone books by pulling on their spines, however much force is applied. It is even possible to suspend a car from them. Using a model that reproduces the traction and friction forces involved, researchers at the Laboratoire de Physique des Solides (CNRS/Université Paris-Sud), Laboratoire Gulliver (CNRS/ESPCI ParisTech), Laboratoire de Génie des Procédés Papetiers (CNRS/Grenoble INP) and McMaster University in Canada have shown that when the spines of the interleaved phonebooks are pulled on vertically, part of the vertical force is converted into a horizontal force that presses on the sheets. The pages then remain stuck together due to friction. The work, which began as a result of a challenge on the program On n'est pas que des cobayes on the France 5 TV channel, will be published in January 2016 in the journal Physical Review Letters, and is already available on ArXiv.

Voiture 1

© France 5/2P2L

vehicle lifted using two interleaved phone books.




voiture 2

© France 5/2P2L

close-up of the interleaved phone books.




Voiture 4

© Frédéric Restagno et Christophe Poulard

Experimental device used in the laboratory to measure the friction force.



Bibliography:

Self-amplication of solid friction in interleaved assemblies, Hector Alarçon, Thomas Salez, Christophe Poulard, Jean-Francis Bloch, Elie Raphaël, Kari Dalnoki-Veress, and Frédéric Restagno. Physical Review Letters, january 2016. ArXiv : View web site

Contacts:

CNRS Researcher l Frédéric Restagno l T + 33 (0)1 69 15 70 78 l frederic.restagno@u-psud.fr
CNRS Researcher l Thomas Salez l T +33 (0)1 40 79 45 52 l thomas.salez@espci.fr
CNRS Press l Alexiane Agullo l T + 33 (0)1 44 96 43 90 l alexiane.agullo@cnrs-dir.fr


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