Many people wonder why their shoelaces are all the time untied, in spite of tying a tight knot. But, the researchers claim that there is science behind it. They claim that the combination of foot stomping and leg swinging cause the laces to slip apart. This is a very obvious reason, but the scientists give reasons to study knots. Knots are everywhere, right from surgeries, to cable constructions. But apparently, the kind of knot tied can also define the strength of the knot.
Types Of Knots
The mechanical engineers were baffled to know that there are two ways to tie the bow-tie knot in shoelaces.
The weaker version is the granny knot – Take a rope, cross both ends left over right, bring the left end under and out, and repeat. The stronger version is the square knot – Instead of repeating the first step, finish the knot by crossing the right end over the left.
To analyse the reason, the researchers attached sensors to shoelace knots as study co-author Christine Gregg, a runner, walked and ran. To better understand, they also repeatedly swung a pendulum arm with the shoelace, so that the forces that a knot experiences, could be analysed.
Slow-motion videos of Gregg running on a treadmill showed that the Granny knot was held together for many strides but once it loosened a little, it failed within another two strides. Intriguingly, the weak knot did not untie while Gregg’s leg was just swung back and forth, or when he stomped his foot on the ground, which meant that the knot failure is dependent upon swing and stomp.
The sensors revealed that while running, the feet strike the ground with seven times the force of gravity, which apparently causes the knots to untie. Researchers claim that the whipping motions of the free ends of the laces, which is caused by swinging legs, apparently makes the laces slip. They also concluded that hanging weights on the laces also makes it slip faster.
Why Study Knots?
Knots are not only present in shoelaces but also in your DNA. Researchers are now building microscopic structures made of DNA and other molecules. The researchers claim that these can involve complex knots in the structure that are subject to different and various forces. These are definitely going to be complicated knotted structures which are important to be understood.
The scientists claim that in order to understand these structures, it is important to study knots and know the reasons behind what makes them untied and how. Building these complex and crucial structures makes, studying knots mandatory. Daily Diamond claimed that further research might throw some light upon why square knots are stronger than granny knots. Also, computer simulations of how the knots work, would disentangle the complex role friction likely plays.