Since thousands of years, shoelaces have been there but they have been relatively poorly understood by the scientists. A new report which would hopefully shed some light on how the dynamic forces that act while running cause the knots to spontaneously get untied.
This usually happens that while you are walking, indulged in your own thoughts, and then all of a sudden when you look down, you realize that your shoes have spontaneously untied themselves for one more time like before. Then you kneel down, retie the laces, and go on walking.
This scenario is familiar to everyone who owns a pair of laced-up shoes. For most of the people, retying their shoes after they untie themselves is one of the life’s little inconveniences that needs to be dealt with from time to time. But for a group of mechanical engineers at the University of California, Berkeley, this spontaneous unraveling of shoelaces became a scientific puzzle. This is so commonplace that no one ever thought of examining it with the kind of disciplined, which is usually reserved for more arcane physical phenomena.
And on Wednesday, the 12th of April 2017, these researchers came up and published a study that represented a significant step toward understanding the physics of what makes a shoelace to unravel while walking or running. They examined how weak and strong knots react to the application of force while a sustainable period of running, shedding light to this common problem that has ben troubling humans for almost a millennia. The researchers hope that their study would provide a stepping-stone to the complex and poorly understood concepts of physics of human’s most basic tool: knots.
“When you talk about knotted structures, if you can start to understand the shoelace, then you can apply it to other things, like DNA or microstructures, that fail under dynamic forces,” said Christopher Daily-Diamond, study co-author and a graduate student at Berkeley, in a statement. “This is the first step toward understanding why certain knots are better than others, which no one has really done“
While previous scientific studies were conducted to understand how knots fail to stay tied up, sustain loads, become undone through the application of short-lived, sudden forces, which are still hard for the scientists to study and discover
For the purpose of examining these forces, the researchers have used a slow-motion camera as a tool to capture the running shoes of Christine Gregg, a graduate student, and study co-author, while she ran on a treadmill. While observing the footage, the researchers have found that the knots were subjected to extreme the pressure from a minimum of two forces, their combined effect was to accelerate the laces at seven times the rate of an object in a free fall, and subjecting them to more than twice the g-force that the astronauts feel while undergoing a rocket launch.
“In particular, there appeared to be two time scales over which untying took place: little change to the knot was observed for many strides until some untying began, after which the speed of untying was remarkable (often in less than two running strides),” the team wrote in the study, which was published in the journal Proceedings of the royal society.
The team then went to test the effect of different kinds of knots and types of shoelaces, having a varying number of results. Then while some knots used to last longer than the others, generally the ways in which the knots failed were remarked to be similar.
“We were able to show that the weak knot will always fail and the strong knot will fail at a certain time scale, but we still do not understand why there’s a fundamental mechanical difference between those two knots,” said Oliver O’Reilly, study co-author, in the statement.Tags: again, knots, physics, shoe, shoelace, untie