At last, the answer to "why do shoelaces get untied by themselves" has been revealed, and it's all thanks to science.
UC Berkeley mechanical engineers conducted the study, and the gist of it is that a combination of striking and swinging motions is the culprit, which was summed up to two stages — a gradual loosening and a "catastrophic failure."
The Test: Treadmill, Running Shoes, And A Slo-Mo Camera
Christine Gregg, also a Berkeley graduate student and coauthor of the study like Daily-Diamond, slapped on some running shoes and proceeded to run on a treadmill as her colleagues captured footage of her motions with a slo-mo camera.
According to the team, shoelaces get untied due to the "force of inertia whipping the laces forward and the stomping of the foot all loosen the knot" — that's putting it simply, though. These motions will continue until the strings finally unravel themselves.
"The forces that cause this are not from a person pulling on the free end, but from the inertial forces of the leg swinging back and forth while the knot is loosened from the shoe repeatedly striking the ground," Gregg said.
Also, the type of knot and lace and tightness all play a big factor in terms of how long it'll take before the shoelaces will come undone.
"Some laces might be better than others for tying knots, but the fundamental mechanics causing them to fail is the same, we believe," Gregg said.
Beyond The Shoelace And Knot Mystery
At first glance, the researchers appear to have carried out the study only to solve the burning question of shoelaces getting untied on their own. However, it's more about getting a better idea of how knotted structures may possibly unravel or fail in certain circumstances when facing various forces.
"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," Christopher Daily-Diamond, Berkeley graduate student and coauthor of the study, said, noting that this is something that no one has done yet.
The Bottom Line
To boil things down, shoelaces will get untied all by themselves eventually, but for that to happen, the wearer will have to create the stomping and whipping motions. Otherwise, it won't occur, which explains why some people will get through the day without having their knots come undone.
"You really need both the impulsive force at the base of the knot and you need the pulling forces of the free ends and the loops. You can't seem to get knot failure without both," Daily-Diamond said.
That essentially means the phenomenon takes place depending on how a person walks, runs, or jogs.
The study is scheduled to be published in the journal Proceedings of the Royal Society A on April 12.
With all said and done, feel free to leave a comment below to let us know what you think of these findings.
