Thursday, August 27, 2015

Interleaved Phone Books

"Physicists Solve the Mystery of Interleaved Phone Books":
A famous demonstration of the counterintuitive power of friction involves two telephone directories with their pages alternately interleaved. People are then invited to pull the directories apart, a futile task since the force required to do the job is mind-bogglingly huge.

Indeed, experimenters have variously tried to separate the directories with trucks and military tanks. They’ve even used them to lift a car off the ground...