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A MYSTERY AS old as laced shoes was unravelled by experiments that reveal how shoestrings come undone when we are on the move.
“The failure of the knot happens in a matter of seconds, often without warning, and is catastrophic,” scientists reported in the journal Proceedings of the Royal Society A.
The researchers meant “catastrophic” in a technical sense of complete, or total collapse – once the loosening begins, there’s no stopping it.
But while the cost of a straggling shoelace is rarely higher than a scraped knee or the time it takes to bend down and retie a bow, sometimes the consequences can be devastating.
Lace-related accidents dot local media around the world: the van driver who killed a motorcyclist when his shoestring – wound tight around the accelerator – prevented him from lifting his foot off the gas; the boy whose leg got pulled into the gears of an escalator; the cyclist who went head-over-handlebars into traffic.
Millions of shoelaces surely come unfurled every day, and yet the mechanics of that process had never been thoroughly examined.
To tackle the enigma, a trio of mechanical engineers at the University of California at Berkeley filmed a knot – on the shoe of a researcher running on a treadmill – coming undone in extreme slow motion.
The images suggested a two-pronged attack on the knot’s integrity.
A double whammy
“When running, your foot strikes the ground at seven times the force of gravity,” stretching and relaxing the knot, said co-author Christine Gregg, a graduate student.
And then – as the knot relaxes – the legs swings into motion, applying additional force.
“A double whammy of stomping and whipping forces acts like an invisible hand, loosening the knot and then tugging on the free ends of your laces until the whole thing unravels,” the researchers explained in a statement.
Follow-up tests with a mechanical foot-and-leg showed that some laces were better than others, but none were impervious to failure.
Of the two most commonly used knots to tie shoes, one is “weak” and the other “strong,” the study found.
The strong version is based on a square knot, which is more symmetrical, while the so-called “false” knot twists when tightened rather than lying flat.
Both fail in the same way, but one takes longer than the other.
“We were able to show that the weak knot will always fail and the strong knot will fail at a certain time scale,” said professor Oliver O’Reilly, whose lab conducted the experiments.
“But we still do not understand why there’s a fundamental mechanical difference,” he added, leaving another knotty mystery to be solved.
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Did I just read this..jasyus I did…I did need to get out more..but nobody has ever explained to me why Broccoli goes cold as soon as you cook it..I’ve never had hot Broccoli yet..
@sparky: Broccoli has a very high surface area per unit weight compared to other veg. This high surface area allows for higher rates of heat transfer to occur between the broccoli and the air. The stems of the broccoli are also a lot less dense than other vegetables too so heat transfer occurs more rapidly for that reason as well.
@sparky: always preheat your plate.
Another valuable scientific endeavour….
Thank God for religion, that’s all I can say.
Stephen Hawking must be glad he is still alive to read this. Good to know scientists have their prioritys right. Serious illnesses & research is not important if shoelaces become undone according to these scientists. This is an insult to scientists everywhere.
@Abcd: If you’d bother to actually read the article you’d see that it does have a serious side in preventing injury.
@Jack Cassady: Guess what Jack… turns out God didn’t do this either…
@Paddy Ryan: My shoelaces have not undone since i was about 6. We where taught too secure all footwear & loose clothing especially near any machinery.
@Abcd: move on to ‘é’ and the rest of the alphabet as soon as you can. Then complete your education, concentrating on logic, but not forgetting reading and comprehension. Then read this article once more. If you do not understand it differently the second time around, you are probably ineducable.
Jasus, this article had me in knots.
Double knot always works for me. Takes2 seconds longer to untie but worth it for one pair of athletic shoes with laces that untie within 10 minutes of tying the knot.
Bunny ears, bunny ears, playing by a tree. Criss-crossed the tree, trying to catch me. Bunny ears, Bunny ears, jumped into the hole, popped out the other side beautiful and bold.”
@Colleen McGovern: what you rabbitin’ on about, Willis?
“…unable to lift his foot off the gas…”
Enough of the Yankisms
Hahaha, yet you use an Americanism in your appeal to eschew a ‘Yankism’!
Enough with the Little Englander mentality. The world uses American English and in Ireland we use, increasingly, American spelling. You can color it whatever way you wish, but the English used in Ireland and in our neighboring island is moving toward the American standard.
Seriously
My guess is it’ll be a combination of vibration from the foot/shoe in normal thread action and the laces swinging. The result of both actions causing the knot to work itself loose.
@Paul Downes: My guess is its explained in the article.
Good on you journal. That’s a fine piece of copy and pasting from a piece of news that was reported on around the globe last week.
So, am I right in thinking a bunch of scientists have basically determined through scientific research that lases come undone because we/i don’t make a proper knot?? Out with lases in with velcro. I think we need a tribunal!
Ah lads, this was solved a long time ago. It’s to do with the direction in which you tie the knot. 3 min video on Ted Talks explains it.
Terry Moore: How to tie your shoes
http://go.ted.com/NQ2rKQ
I kid you knot!!!
Who the hell finds this kind of research ? The scouts ?
#Funds#
Jesus these lads are busy
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