The frustration of untied shoelaces has plagued parents, children, and teachers for generations, but no one has ever been able to explain why shoelaces won’t stay tied. However, now scientists at the University of California Berkley have studied the phenomenon and discovered an answer.
Science Found An Explanation For Why A Shoelace Comes Undone
The shoe string theory, investigated by mechanical engineers at UC Berkeley shows that two very different types of forces cause a shoelace knot to come untied. The force of a foot hitting the ground makes a knot looser, and the motion of a leg moving back and forth causes the ends of the laces to become unraveled. The striking force results in the knot repeatedly stretching out and relaxing while the swinging motion puts a force of inertia on the ends of the lace, permitting it to become untied. The two actions combine to cause a failure of the knot because of the changing forces and loads on the laces.
The study, which was released in the Proceedings of the Royal Society A, was led by study co-author Christopher Dailey-Diamond, a graduate student at UC Berkeley. Besides answering the age-old question of why shoelaces won’t stay tied, the study has other important implications as well. This research can be useful in answering questions about the DNA or other microstructures.
While the research reported by the UC Berkeley mechanical engineers shows how a standard shoelace knot fails, it doesn’t indicate what kind won’t fail. The study pointed out the quick failure of what is known as a “false knot”, in which the laces twist when they’re tightened instead of lying flat. Such a structure, based on a square knot, delivers the preferred flat angle, but the knot still fails, although not as quickly.
UC Berkeley researchers say they are interested in delving more deeply into the reasons why these different types of knots come untied, although at diverse lengths of time. Scientists want to understand the mechanics that cause apparently different actions to result in the same consequence.
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