Why newspapers tear the same way

And tongues of shoes slipping to the outside

Dear Matthew Alice: Why does a newspaper tear straight vertically, but not horizontally? Also, why do the tongues of tennis shoes always slip over to the outer side of the shoes when you wear them? Always wanted to know. —Erica, San Diego

Newsprint is made from wood pulp that’s been crunched into thin fibers. At some point in the papermaking process, they jiggle the fibers in water to get them going more or less in the same direction, giving the paper what’s called a “grain.” Tear the paper in the same direction as the grain and everything’s tidy. Tear against the grain, and you’ll get that raggedy edge, since the paper will “give” in the weakest spots, at the ends of the pulpy threads. As for the shoe dilemma, the standard answer says it’s a function of your particular bone structure, foot-pressure pattern, and shoe design. Personally, I think it’s our Nikes’ way of making a break for it. Those single shoes that you see by the side of the road? Escapees on their way to join all those socks that vanish from the laundry.

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