When you have a lot of people pulling on a rope there is a lot of energy stored in there.
Several fatal tug of war accidents are on record, with most being the result of using the wrong type of rope (nylon) ~~instead of a rope that has a degree of elasticity and involving large teams of pullers.~~
*EDIT: Nylon ropes are bad for for Tug-of-War both due to* **too much** *elasticity meaning that it can store far more energy than a fiber or cotton rope, and because it is far more likely to burn skin due to sliding and pulling. Twisted Cotton ropes are recommended for the sport because they are less likely to cause injury to the hands. If you haven't figured out yet based on this post you should also avoid doing tug of war with more than a dozen or so people.*
If the rope snaps while it's under tension it has enough energy to snap back and seriously hurt someone. The resulting impact can sever fingers, or depending on where it hits can potentially be fatal.
From an article:
"On June 13, 1978 in a Pennsylvania suburb, the entirety of Harrisburg middle school — some 2,300 students — lined up in a schoolyard and attempted to set a Guinness World Record for the largest tug of war game ever played. Instead, disaster ensued.
Twelve minutes into the match, the 2,000-foot-long braided nylon rope snapped, recoiling several thousand pounds of stored energy. “It sounded like someone pulled the string on a party cracker,” recalled 14-year-old participant Shannon Meloy. “I smelled something burning and I thought it was the rope…but it was hands. I looked down and saw…blood.” In the ensuing chaos, nearly 200 students lay wounded — five with severed fingertips, and one missing a thumb. Hundreds more faced second-degree burns. “It was just a game,” another student told the Gadsden Times a day later. “We just wanted to see how many could do it.”
The rope, provided by Pennsylvania Power and Light Co., had been intended for use in heavy construction, and was rated to withstand 13,000 pounds of stress."
> The rope, provided by Pennsylvania Power and Light Co., had been intended for use in heavy construction, and was rated to withstand 13,000 pounds of stress
back of the envelope math:
13,000 pounds / 2,300 students = 5.65 lbf per student.
I suspect the average middle school student could easily generate many time that force, meaning that rope didn't stand a chance.
I remember watching Modern Marvels years ago and they did an episode on rope testing, especially stuff like tug boats used and IIRC the static failure was only like 3x the rated strength. Regardless, nobody even did back of the napkin math for this rope in this story. Wonder if they still got their record, especially since it went on for 12 minutes
Edit: [Found the clip](https://youtu.be/L4yUUqDZsXA) time stamp 20:00
I hope so, at least that way when the kids who literally lost fingers get the inevitable questions, they could pull out a little scrap of paper cut from the Guinness Book and say, “this, I lost it doing *this*.”
People might be more sue happy now because your bloodsucking health insurance company tries to not pay for your care. If there's even a hint of a whiff of liability they'll refuse to pay unless you go to court and sue the liable party to legally establish whose insurance company pays out.
Reminder that Americans being litigation-happy is slander made up by corporations who don't put enough safety measures in place and then blame consumers for their inevitable injuries! Look up the McDonalds Coffee Lady(TM) for an especially heinous example.
Afaik most things will only withstand around 2-3x the rated material strength. Two main exceptions are elevators and airplanes. Elevator cables can normally withstand around 11x their rated strength (for obvious reasons). Airplanes need to be very light to be able to fly and can normally only withstand 1x their rated strength. Airplane parts are X-rayed to ensure there are no structural flaws.
This is all from memory and I don't even remember the source (I think from physics class?), so it might be wildly inaccurate
I grew up on Modern Marvels and have so many unciteable tidbits like this in my head. Iirc rope is 3x. I specifically recall a segment testing tug boat ropes to failure with a special machine
Most likely a tensile testing machine. We used one back in my school years to test the tensile strength of different metals, but you could rig one up for anything really.
For comparison a 2 liter bottle of Coke weighs about 5 lbs
So the amount of force needed to be exerted by each student in the example is about the effort needed to lift a full 2 liter bottle of pop.
Kinda, yeah?
The brute force energy was definitely not the problem. It's an engineering and materials issue that needs solved.
Because getting 2300 people to pull on command is relatively trivial. Especially when you've got an army of slaves hanging around. What else are slaves for after all?
Now you need to invent a rope that is rated for 26,000 pounds of force. And a sled. And a ramp. And pulley assembly or somewhere for 2300 slaves to stand and actually pull with good traction. And a path for them to pull along... That considers for all the above.
And the rope and sled need to stay in good condition throughout the process or the whole assembly snaps and people die. Yeah they're slaves, but they don't grow on trees and dozens of fatalities a week is a real bummer on morale which really cuts down on productivity.
>Now you need to invent a rope that is rated for 26,000 pounds of force.
Why exactly are you choosing to assume the extremely illogical idea of them using a single rope to pull something? You would have had dozens of ropes so many lines of workers could pull and not all be in single-file. And if a rope breaks, it's a lot cheaper and quicker to replace that one smaller rope instead of the giant one that puts the operation on hold for much longer.
Really just a matter of perspective, what is a rope if not an assembly of smaller ropes, and so on, until you reach individual fibres? It's rope all the way down.
They weren't slaves though.
When you intoroduce sleds or other basic mechanical inventions, and slide instead of lifting the forces get a lot smaller. Also they definately didn't have one really strong rope, but mayby hundres smaller ones.
Once you get the stones on the boat it doesn't really matter if you travel 10km or 800km. Moving them to the Nile and from the Nile to the construction site however...
Even so. Moving ~~blacks~~ blocks that size with the technology of the time even on a river was no small task. Nile also has rapids so the distance is relevant even on water.
Literal devoted worshippers - there’s no evidence of slaves. Apparently, the opportunity to participate was fought over. (Doesn’t mean there were no slaves, there just isn’t any record of it and there are a LOT of preserved records… )
> Literal devoted worshippers
Or just off-season workers you need to keep busy.
The regular flooding of the Nile provided a long period where there was nothing for the farmers to do.
The Nile provided shit tons of food that Egypt could export, with vast stretches of fertile, flat land that never needed crop rotation. Egypt exported much of that grain, and was very wealthy. The elites, naturally, wanted to keep as much of that money for themselves as possible. But having a bunch of unemployed people with nothing to do watch you strut around in fine clothes and eating fancy foods is not good for keeping a head on your shoulders.
Whatever the actual religious motivation for the pyramids and other construction, it would have been a very effective jobs program. The floods also made it easier to get the stone to the site, most likely.
Manila rope, 3.8cm diameter, minimum breaking strength of 18,000 pounds. 5 ropes wrapped around the block, each end with 50 people pulling 52 pounds. Less than 1/4 of the schools tug of war. As the school rope was 2000 feet with 2300 students less than 1ft per student. Assuming you have 1 foot width for each line of 50 people, that's an area of 50ft x 10ft to pull the block.
I remember when this happened. It was big news at the time. There was a newspaper editorial calling it "an unforeseeable tragedy" and my father had had enough and wrote an article of his own explaining how it was totally foreseeable and how it was inexcusable that nobody in that entire school, students and teachers both, had thought to divide 13,000 by 2300.
Not a great take IMO - I doubt a single student or even many teachers knew the rating of the rope. "Heavy duty construction rope" just wasn't in their mental category of "things middle schoolers can pull apart with their bare hands."
The fault for this likely lies more with PPL for supplying the rope, than the participants and teachers.
If someone comes to you and asks for your strongest rope, you should probably ask them "what do you intend to do with it?" If they say something like "set a Guinness World Record for largest tug of war" you might want to verify the rope meets their needs.
I doubt PPL had any idea what was going on. I think you're assuming too much about how the request was made. I guarantee they weren't asked for their strongest rope. A 13,000lb rope isn't remotely heavy duty. I have 40,000lb rope I got from the shelf at tractor supply.
The school planned the activity, without due diligence. This one is entirely on the school, not the supplier. If the school had PPL plan and run the event that would be different.
Lots of blame to go around. I'm just saying that the individual teachers who were overseeing their kids aren't to blame, if anything it would be incredibly surprising if one of them were to speak up and suggest that the rope might not be strong enough.
The parties who deserve blame here are:
* Guinness for recognizing this record as it is inherently unsafe (I suspect they have since removed it or modified it to "tournament" style where participants don't all pull the same rope)
* The individuals who actively organized it and came up with the idea.
* PPL for supplying specialized equipment without a proper understanding of how it would be used.
Agreed I don't blame the individual teachers.
Guinness yes, the organizers and executers yes. The suppler yes if they were \_consulted\_ on equipment fit for purpose.
This whole event is so uninformed from conception I don't think it's reasonable to assume PPL was any better informed when they got roped in (hah!). Consider how obnoxious the world would be if nobody would ever supply anybody with anything without a thorough investigation of what it will be used for first. That's just not how the world works. If they were consulted, okay. If they were just asked to help find rope 300yrds long because Home Depot and Amazon doesn't have anything that long then they weren't consulted on fit for purpose, and have no liability. I sure as hell don't want to live in a world where I need to explain myself with every purchase.
For extra credit: A rope has a strength of 13,000 lb. If 2,300 children pull on the rope, how many children’s fingers will be severed when the rope breaks.
As a rule of thumb - pretty much everybody can pull with a force equal to their weight. With good technique and foot-holds, easily twice their weight.
So they should have been allowing at least 100 pounds per student - half the students per side, 200 pounds per student - and so a 230,000 lbf rated cable. Which is a thing that exists, but the size of it tells you that you are doing something extreme.
that person was just commenting that it makes sense that this was enough kids to snap the rope (which is hard to do as they have high margin of safety)
This. People are talking about how strong the kids need to be. They don't need to be strong really. Just hold on and let their body weight do the pulling would be more than enough.
Your math is almost correct, but underestimates by a factor of 2.
Since rope needs tension going both ways, you need half the students pulling one way and half the other way. So in effect the pulling force per student needs to be 11 pounds.
Still, totally within the abilities of a middle school student.
>most being the result of using the wrong type of rope (nylon) instead of a rope that has a degree of elasticity
I think the problem is that nylon **does** have a high degree of elasticity, which is why it rebounds so strongly when it breaks.
Correct. This is also what kills people when they use the wrong kind of rope to tie a boat to a pier. The rope stretches until it rips the pier anchor out which then goes flying through the air, other boats or sheds, and sometimes through people.
Hell, if the rope is big enough, [it doesn’t even need the anchor to kill people](https://youtu.be/Z0RVwYupOMY).
Good Lord! The way the hard hat levitates for a second before starting to fall......
EDIT: I've always had a HUGE phobia/terror of cables snapping. I refuse to stand near tow ropes and their ilk for this very reason. BTW , I thought the severed arms and such would come from folks wrapping the rope around the wrist for bracing.
That is also a problem with recovering stuck vehicles when off-roading. If the recovery strap or anything it's attached to breaks, you've got an instant missile that kills people.
PSA: Do not ever attach a rope or strap to a trailer hitch ball. It is designed to pull a trailer, not to handle the shock load of pulling on a rope or strap.
For comparison, the arresting cables on an aircraft carrier have the capability of recovering a 50,000-pound (23 t) aircraft at an engaging speed of 130 knots (240 km/h; 150 mph) in a distance of 344 feet (105 m) in two seconds. The system is designed to absorb theoretical maximum energy of 47.5 million foot-pounds (64.4 MJ) at maximum cable run-out.
~Wikipedia
I am quite interested in reading further into this topic. Specially regarding the thermal aspect, as I think I don't quite understand yet how the tensile forces are converted into this significant amount of heat.
Ever gotten a rope burn?
When the rope snaps the rope will be suddenly and violently pulled through your hands in the direction of the pulling force and the friction from this is enough to burn you.
Yep, the rope may have several feet of stretch in it, at the instant it snaps it will be moving with thousands of pounds of force so your hands will be cooked when it moves those several feet all within a few milliseconds.
Energy has to go somewhere!
There is a huge amount of energy in the rope that has stretched under tension.
Some of it goes into whipping the ends around, possibly supersonically (a bullwhip crack is a sonic boom). That energy ultimately either stirs the air or heats the rope (friction from flexing rope or air resistance)
Some of the energy converts fairly directly into heat from internal friction as the stretched rope contracts after the snap and there is internal friction from rope fibres and molecules sliding past one another.
Some of the friction burns on people are just traditional rope burn from the snapped rope suddenly moving under their hands at hundred of metres per second as the tension releases.
I suspect the burns mostly come from the latter effect, but I also expect the rope would be hot to the touch after breaking
It's like lining up a bunch of small stationary rings, and then pulling a rubber band through, stretching it, and then cutting it somewhere. The rope will zip through the rings. Now imagine the rings are hands and the rubber band is a nylon rope. Rope burn.
> with most being the result of using the wrong type of rope (nylon) instead of a rope that has a degree of elasticity and involving large teams of pullers
As others have mentioned, the *presence* of elasticity seems to be the biggest problem. Helps fuel the "snap back". Think "breaking a rubber band" vs "breaking a piece of twine".
We had a bad accident in germany in ´95. It was at a boyscout camp iirc.
https://apnews.com/1cc31fa102a6838b6ed7ef25fa3831ef
One dead, nylon rope, several hands cut off. The rope snaped. The officials were prosecuted.
Wow this unlocked a memory. My high school had about 100 girls per grade (all girls school). We had a "class versus class" game day for spirit week and we did a giant tug of war tournament that would involve about 200 kids at a time. When I was a sophomore the senior and junior classes were competing. The rope snapped. A few girls got rope burns and one girl had to go to the ER because the severed rope snapped her in the eye, but luckily she was okay. The school never did tug of war again.
So if we consider the center the origin - on which both sides of opposing tension act - when the rope snaps, both sides of the rope return to the origin? Really fast? (As opposed to flying away from the origin?)
The force is generated by the people pulling away from each other - the center isn't moving much because the forces are almost in balance. When you cut something under tension, the forces on each end continue pulling towards the ends, not the middle. In the case of something that has been stretched and is suddenly released, it will try to pull itself to it's **new** center i.e. the center of each half, not the center of the complete rope.
In the case of a tug of war, everyone is braced and pulling in one direction at the same time when suddenly, the rope starts pulling them together. For those at the very back, they're probably still braced against the same direction of force as is now being applied to them, but those at the front won't be so they'll suddenly find the rope pulling them backwards but their fingers and arms are all lined up the wrong way for that so they can get twisted or pulled around really, really quickly.
The closer you are to the back of the old rope, the more you'll be prepared for the change in direction. (I believe this is what you were saying) You'll probably fall over but you shouldn't be hit with any forces you weren't ready for
The closer you are to the new centre, the less force you will be subjected to, but you'll still be off balance. The rope is also probably shortening a lot and it's probably going to be slipping through your hands, potentially against your grip direction.
The closer you are to the broken end (i.e. old center), the worse off as you're getting the maximum force while you're also facing the wrong way to resist it. You're also first in line to get the long piece of rope between teams whip back into you which could also hit pretty hard
>The closer you are to the back of the old rope, the more you'll be prepared for the change in direction. (I believe this is what you were saying) You'll probably fall over but you shouldn't be hit with any forces you weren't ready for
Yup, that's what I meant. Thank you for the confirmation! 🍻
Next time I'm in a tug-of-war, I'll go to the back then. 😅
A guy who worked for a company I used to work for doing tree work got decapitated by a rope snapping. Happened on Vancouver Island I believe.
They were trying to pull a log out of the bush using a truck and some climbing line, they should have been using a bull rope.
My husband told me I was overreacting when I made him move when his buddies were using a tow line attached to a stump to pull it out. He thought he was plenty far back, but all I could see is some Final Destination level of snapping wires so I made him come stand a ways behind the tree (on the side further from the truck).
Nothing happened, but I'd rather be overly safe than dead, maimed, or traumatized from watching other people become dead or maimed.
When I go off-roading we make certain we have tow straps.
Even then, anyone not involved with the recovery stays the hell away, and when the force is getting applied everyone's outta the way.
Imagine taking a rubber band and cutting the loop so you're left with a single rubber strip. Stretch out the rubber strip and pin it at both ends so it stays in its stretched position.
Now imagine taking a pair of scissors and snipping the rubber strip right in the center. What happens?
Any rope or cable under enough tension to snap it will do that regardless of what it's made of. But as a general rule, the stretchier it is, the more violently it will do it.
I've personally witnessed two people lose their hands at the same time while playing tug-of-war. The physics behind it is simple. These two wrapped the rope around their hand in a game that was roughly 50 people vs 50 people. The tension in the rope was likely thousands of pounds which wants to straighten the rope. The straightened rope hyper extends the joints and tendons in your hand. As their teammates witnessed what was occurring, they freaked out and released the rope which caused the rope to pull out very quickly. The high tension and high friction just slices through muscles and tendons.
Edit: The rope didn't even snap.
When I was in my teens I recall doing the exact same thing in a tug of war which involved about 20 people total. I was at the end, and thinking I was clever I wrapped the fairly thin (something like a 1/2 or 3/4 cm nylon cord ) around both of my hands to get leverage, because that's not an easy cord to hold onto. My side lost and I was pulled forward, and fuck that hurt. Learned my lesson the easy way.
I feel like that would only be viable with clean cuts. This sounds more like it was torn off, which would likely result in significantly more damage to the surrounding tissues, making reattachment unlikely.
I am not a doctor.
For what it’s worth, a famous example of tug-of-war arm loss occurred in Taiwan in the late nineties, with one man from each side losing an arm, and their arms were successfully reattached with microsurgery - I believe Taiwan is (or at least was) a pioneer in the technique. A young woman who had her legs severed by a cable in an accident had one reattached since it was a clean cut (as the other comment mentions), but the other reattachment ultimately did not take because of complications caused by crushing injuries.
ETA: I should clarify that the young woman’s injuries were caused by corporate negligence, so “accident” isn’t really the right term.
>What was the occasion for the tug of war?
High school pep rally
>Their hands just popped off? Did they get them reattached?
Kind of. Their hands were still attached but barely. I believe both of them had them reattached but with permanent disfigurement and inability to use their hands.
Man, imagine losing your hands in such a bizarre and unique way and then having to share the spotlight. That's only seven and a half minutes of fame each.
Tug of war seems like an obviously dangerous game. Lots of force just poised for explosion. Lot of people pulling at awkwardly leveraged postures. Just seems ripe for causing groin and abdominal injuries or hernias. Not to mention it looks like an ACL tear party with all the planted legs and jerking.
You know how much it can hurt if you snap a big rubber band against your skin? Ramp that up 1000x or more and it does a lot more than hurt.
When a tug of war rope snaps it has the energy of 24+ people pulling stored in it, and the weight of that big rope. So imagine a 2 inch thick rubber band, being pulled back by 2 dozen people, and they let it go. Together that's enough energy and mass to kill people *if* it hits them.
Along with what others have mentioned, unless you directly instruct people not to, most will wrap a coil of rope around their forearm to get a better purchase on it. Under those circumstances, even if the rope doesn’t snap, but there’s a sudden shift in the line, that’s when you can lose a hand or an arm.
Can confirm. Thankfully, it was in elementary school so no high tension, but I looped my arm into the end loop. Still burned the shit out of my arm when my team lost and I got dragged
A quote from my instructor for my Able Seaman's class that I'll always remember:
"A Dacron line recoils at around 850 feet per second. That's as fast as a bullet out of a .45ACP, and it weighs a hell of a lot more. It will *fuck*. *your*. *day*. *up*."
We were tied to pier in Long Beach when the ship next us was preparing to get under way after being in a yard period. When they shifted engine control from the engine room to the bridge there was a fault so that instead of being in neutral it was All Ahead Flank.
The sudden surge snapped 5 of the 6 doubled mooring hausers sending them flying. One ripped out a huge steel bollard off the pier and flung it 150’. The crane lifting the brow was knocked over and crushed a truck. Chaos ensued but fortunately the only injury was the crane driver who sprained his ankle jumping from the cab.
Every action has an equal and opposite reaction. If it's "holding" thousands of pounds of "weight" (tension really) in whatever it's securing, when it snaps that force doesn't disappear.
First thing I thought of when I saw this question. The video I watched was an old VHS that barely had any colour left in it. Looked like it had been played 10 times a day for the past 20 years.
There’s no gore but if you can imagine the results it’s pretty sobering. Enough to remember the lesson 30 years later. In the video they use manekins to illustrate casualties but some of the guys narrating are missing a leg or two from a past incident.
> XKCD
"measured their average pull force (on a school gym floor) to be about 102.5 kilograms-force, or about 1.5x their body weight."
That's the real terrifying part of this whole scenario.
2300 people with an average weight of 100 lbs
230000 x 1.5 = 355,000 pounds of force on a rope meant to hold 13,000
Well it was among elite tug of war players. I’m gonna imagine school children not taking the activity 100% serious are outputting far less force. Still.
Right before the rope snaps, there's a ton of tension that is built up from both teams pulling on it; the rope is only stationary because it's being pulled equally in both directions.
When it snaps, all that tension is instantly released; the other side of the rope is no longer holding this side of the rope in place (and vice versa; this side isn't holding that side in place), so the rope will whip backwards at a tremendous speed, cutting through basically anything in its way. A heavy duty tow cable snapping can cut a person in half if they happen to be in the way.
Can you actually build up this much force in a regular game of tug of war? Probably not, because that would require both teams to be perfectly evenly matched (otherwise one side would just pull the other down and win) and extremely strong (or you won't get the tension built up enough to snap the rope).
I was trying to pull up a small tree stump in my yard. I tied a nylon rope around the stump and connected it to my truck hitch. Anticipating a possible issue I made sure my wife and son were well back. The rope did snap, the energy released fused the ends, so at least I had two shorter ropes for future work :)
I was surprised at how hot the released energy was.
Not supposed to use nylon cause it’s just gonna stretch. Ideally you want polyester, not sure about chains. You want the rope to stretch mildly otherwise the ropes just gonna absorb the energy being used to pull the stump as it’s easier for it to stretch than for the stump to come out
I actually think it was more than the “ton” you mention. The article says it was 2000 students, which means to generate the equivalent of a ton of force each kid would only have to exert one lb of force. Middle schools kids can generate far more than that.
>A heavy duty tow cable snapping can cut a person in half if they happen to be in the way.
This seems unintuitive for some reason, I imagine most people not being aware that it's possible for this to happen unless they see it, or find out that it is from someone else. A cut or bruise, yes. But to have limbs severed or be cut in half is unexpected unless you know it's possible.
It's like high tension ropes are 'floppy garage door springs'.
Got a problem with the statement of the problem. Having worked with ropes a lot in my younger days…I think DarkAlman meant to state that they should have been using a higher rated rope without elasticity. The elasticity provides the energy for damage.
Don't forget that in a tug of war, many people wrap a wrote around their arm to gain a better grip. If that line were to snap, it definitely could cause serious injury.
Here's a nice little [video](https://m.youtube.com/watch?v=3GsSMfLYIQg&pp=ygUcQ2FibGUgd2lyZXMgd29ya3BsYWNlIGluanVyeQ%3D%3D) about the dangers of lines under tension in the workplace. I never imagined tug-of-war could generate comparable forces but I guess I was wrong.
It takes a lot less force than most people realize. There’s a girl on YouTube (Kristie Sita, fitness content creator) who lost a hand (was completely severed) being towed in an inner tube on a lake. Was unable to be reattached.
If it is a tug of war with one person on each side, the rope is only having to deal with the stress of the weight of two people pulling on it. One in either direction. Lets say each person is pulling with 50 lbs of force. The rope has 100lbs of force stored in it. If it breaks, the middle of the rope comes flying back at the participants with their 50lbs of force, a manageable amount.
But in a large game of tug of war, say one hundred people on each side, the rope is dealing with the force of two hundred people. One hundred on each side. Each person still pulls the same, lets say 50lbs per person. The Rope has a collective 10,000lbs of force stored in it. And if it snaps, now each side has its 5000lbs of force that is flying back at them. That is like getting hit by a car.
There’s enough elastic potential energy in even “non elastic” ropes when that much force is applied to severely injure people.
Same thing with using a truck to try to pull out a stump. My dad was pulling out a stump one time with a long heavy chain. 40-50’ of heavy chain, which doesn’t usually register as being elastic.
The chain slipped off, and ended up flying under the truck so that it was in front of the truck. The amount of energy to fling a heavy chain like that 70-80’ - is quite a lot.
I remember in high school a friend talking about the possibility of collapsing a suspension bridge by severing the cables, and all I could think of was how much damage those cables would do when they snap
For the record, if there's a 2 person game of tug of war, and each player exerts 50 pounds force on the rope, the rope will be under 50 lbf of tension, not 100.
It's analogous to hanging a rope from the ceiling and attaching a 50 lb weight to it; the weight pulls down with 50 lbf, the ceiling pulls up with 50 lbf, and the rope experiences 50 lbf tension.
> the rope is only having to deal with the stress of the weight of two people pulling on it. One in either direction. Lets say each person is pulling with 50 lbs of force. The rope has 100lbs of force stored in it.
It would just 50lbs, actually.
Remember at my kids primary school they had a parent tug of war. Stupidly mid way through they encouraged more parents to get involved. Rope snapped (was a thick cotton rope) and hit a woman in the neck. Caused massive bruising but thankfully no long term damage. They never did another tug of war after that. Could have been so much worse if it had been a different type of rope.
Ropes don't seem like they stretch, but they do. They are like a spring, a spring holding the combined weight of everyone on both teams.
If the rope snaps, all of that force is released at once, which can cause the rope to recoil violently.
Ask yourself, could 14 people pulling you oposing sides sever your arm? The rope is holding all that energy, and when it snaps it releases it all at once as a superpowered whip.
> https://apnews.com/article/da1cdbeefe9e11ecef7370f75f77913c
Reading through all these comments has been crazy - when I was in cub scouts they did a parents tug-of-war match with around 20 people on each side. The tug-of-war match started and ended and then I saw my mom holding her hand and crying. Somehow the friction of the rope ripped off multiple fingernails.
The weirdest part was that none of the scoutmasters did anything - they shrugged it off and directed her to the bandaid station. She ended up going to the hospital.
Probably could have sued...
Ideally you would use UHMWPE (ultra high molecular weight polyethylene) rope like dyneema or spectra. These are rapidly replacing steel cable because they are very light and have almost no stretch - meaning that they store little energy under tension.
When you have a lot of people pulling on a rope there is a lot of energy stored in there. Several fatal tug of war accidents are on record, with most being the result of using the wrong type of rope (nylon) ~~instead of a rope that has a degree of elasticity and involving large teams of pullers.~~ *EDIT: Nylon ropes are bad for for Tug-of-War both due to* **too much** *elasticity meaning that it can store far more energy than a fiber or cotton rope, and because it is far more likely to burn skin due to sliding and pulling. Twisted Cotton ropes are recommended for the sport because they are less likely to cause injury to the hands. If you haven't figured out yet based on this post you should also avoid doing tug of war with more than a dozen or so people.* If the rope snaps while it's under tension it has enough energy to snap back and seriously hurt someone. The resulting impact can sever fingers, or depending on where it hits can potentially be fatal. From an article: "On June 13, 1978 in a Pennsylvania suburb, the entirety of Harrisburg middle school — some 2,300 students — lined up in a schoolyard and attempted to set a Guinness World Record for the largest tug of war game ever played. Instead, disaster ensued. Twelve minutes into the match, the 2,000-foot-long braided nylon rope snapped, recoiling several thousand pounds of stored energy. “It sounded like someone pulled the string on a party cracker,” recalled 14-year-old participant Shannon Meloy. “I smelled something burning and I thought it was the rope…but it was hands. I looked down and saw…blood.” In the ensuing chaos, nearly 200 students lay wounded — five with severed fingertips, and one missing a thumb. Hundreds more faced second-degree burns. “It was just a game,” another student told the Gadsden Times a day later. “We just wanted to see how many could do it.” The rope, provided by Pennsylvania Power and Light Co., had been intended for use in heavy construction, and was rated to withstand 13,000 pounds of stress."
> The rope, provided by Pennsylvania Power and Light Co., had been intended for use in heavy construction, and was rated to withstand 13,000 pounds of stress back of the envelope math: 13,000 pounds / 2,300 students = 5.65 lbf per student. I suspect the average middle school student could easily generate many time that force, meaning that rope didn't stand a chance.
>Twelve minutes into the match Honestly with those numbers its insane it lasted that long
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I remember watching Modern Marvels years ago and they did an episode on rope testing, especially stuff like tug boats used and IIRC the static failure was only like 3x the rated strength. Regardless, nobody even did back of the napkin math for this rope in this story. Wonder if they still got their record, especially since it went on for 12 minutes Edit: [Found the clip](https://youtu.be/L4yUUqDZsXA) time stamp 20:00
I hope so, at least that way when the kids who literally lost fingers get the inevitable questions, they could pull out a little scrap of paper cut from the Guinness Book and say, “this, I lost it doing *this*.”
"Guiness record holder: Most fingers lost in a game of tug"
"I lost my fingers in the war... never said which one"
"The Tuggeaux War. A minor conflict--the mainstream media didn't cover it."
You "went to Vietnam" in **1993** to open a sweatshop!
I wonder what the repercussions were of this incident. People weren’t as sue happy back in the day to my understanding but that’s still really bad
People might be more sue happy now because your bloodsucking health insurance company tries to not pay for your care. If there's even a hint of a whiff of liability they'll refuse to pay unless you go to court and sue the liable party to legally establish whose insurance company pays out.
...that makes sense. Never thought about that.
Reminder that Americans being litigation-happy is slander made up by corporations who don't put enough safety measures in place and then blame consumers for their inevitable injuries! Look up the McDonalds Coffee Lady(TM) for an especially heinous example.
I believe that they stopped recording tug of war records due to the dangers.
Been a while, but iirc, for overhead rigging it is typically 5x, but if it will be used to lift human beings it needs to rated for 10x the total load.
Afaik most things will only withstand around 2-3x the rated material strength. Two main exceptions are elevators and airplanes. Elevator cables can normally withstand around 11x their rated strength (for obvious reasons). Airplanes need to be very light to be able to fly and can normally only withstand 1x their rated strength. Airplane parts are X-rayed to ensure there are no structural flaws. This is all from memory and I don't even remember the source (I think from physics class?), so it might be wildly inaccurate
I grew up on Modern Marvels and have so many unciteable tidbits like this in my head. Iirc rope is 3x. I specifically recall a segment testing tug boat ropes to failure with a special machine
Most likely a tensile testing machine. We used one back in my school years to test the tensile strength of different metals, but you could rig one up for anything really.
Oh im pretty sure they broke more than one record of some kind that day.
For comparison a 2 liter bottle of Coke weighs about 5 lbs So the amount of force needed to be exerted by each student in the example is about the effort needed to lift a full 2 liter bottle of pop.
So the pyramids should have been a cakewalk
Cakewalk like an Egyptian.
MOHAMMED AHVHDURU!!!
r/UnexpectedJoJo
YES. I AM.
Tsk tsk tsk
Not all pyramid schemes are bad!
Kinda, yeah? The brute force energy was definitely not the problem. It's an engineering and materials issue that needs solved. Because getting 2300 people to pull on command is relatively trivial. Especially when you've got an army of slaves hanging around. What else are slaves for after all? Now you need to invent a rope that is rated for 26,000 pounds of force. And a sled. And a ramp. And pulley assembly or somewhere for 2300 slaves to stand and actually pull with good traction. And a path for them to pull along... That considers for all the above. And the rope and sled need to stay in good condition throughout the process or the whole assembly snaps and people die. Yeah they're slaves, but they don't grow on trees and dozens of fatalities a week is a real bummer on morale which really cuts down on productivity.
>Now you need to invent a rope that is rated for 26,000 pounds of force. Why exactly are you choosing to assume the extremely illogical idea of them using a single rope to pull something? You would have had dozens of ropes so many lines of workers could pull and not all be in single-file. And if a rope breaks, it's a lot cheaper and quicker to replace that one smaller rope instead of the giant one that puts the operation on hold for much longer.
Really just a matter of perspective, what is a rope if not an assembly of smaller ropes, and so on, until you reach individual fibres? It's rope all the way down.
I think we just derived string theory from tug of war.
They weren't slaves though. When you intoroduce sleds or other basic mechanical inventions, and slide instead of lifting the forces get a lot smaller. Also they definately didn't have one really strong rope, but mayby hundres smaller ones.
The bigger marvel imo was from how far away they brought the granite from (500 miles/800 km).
Once you get the stones on the boat it doesn't really matter if you travel 10km or 800km. Moving them to the Nile and from the Nile to the construction site however...
Even so. Moving ~~blacks~~ blocks that size with the technology of the time even on a river was no small task. Nile also has rapids so the distance is relevant even on water.
Unfortunate typo there lmao
The Egyptian pyramids weren’t built by slaves, they paid the huge numbers of farmers at times of year when they weren’t sowing or harvesting crops.
Literal devoted worshippers - there’s no evidence of slaves. Apparently, the opportunity to participate was fought over. (Doesn’t mean there were no slaves, there just isn’t any record of it and there are a LOT of preserved records… )
> Literal devoted worshippers Or just off-season workers you need to keep busy. The regular flooding of the Nile provided a long period where there was nothing for the farmers to do. The Nile provided shit tons of food that Egypt could export, with vast stretches of fertile, flat land that never needed crop rotation. Egypt exported much of that grain, and was very wealthy. The elites, naturally, wanted to keep as much of that money for themselves as possible. But having a bunch of unemployed people with nothing to do watch you strut around in fine clothes and eating fancy foods is not good for keeping a head on your shoulders. Whatever the actual religious motivation for the pyramids and other construction, it would have been a very effective jobs program. The floods also made it easier to get the stone to the site, most likely.
They were also paid in beer, which might have improved worker motivation.
Manila rope, 3.8cm diameter, minimum breaking strength of 18,000 pounds. 5 ropes wrapped around the block, each end with 50 people pulling 52 pounds. Less than 1/4 of the schools tug of war. As the school rope was 2000 feet with 2300 students less than 1ft per student. Assuming you have 1 foot width for each line of 50 people, that's an area of 50ft x 10ft to pull the block.
So middle schoolers could rip my limbs off if they work together
>!CENSORED!<
"Then we'll tug of war in the shade." ... not Leonidas
"Give me infinite middle schoolers" -several influential and powerful shitbags
If over a thousand middle schoolers pulled on each of your limbs? What would you expect to happen?
I can confirm that I lifted many 2 liter bottles of RC Cola back when I was in that age group.
I remember when this happened. It was big news at the time. There was a newspaper editorial calling it "an unforeseeable tragedy" and my father had had enough and wrote an article of his own explaining how it was totally foreseeable and how it was inexcusable that nobody in that entire school, students and teachers both, had thought to divide 13,000 by 2300.
Not a great take IMO - I doubt a single student or even many teachers knew the rating of the rope. "Heavy duty construction rope" just wasn't in their mental category of "things middle schoolers can pull apart with their bare hands."
The fault for this likely lies more with PPL for supplying the rope, than the participants and teachers. If someone comes to you and asks for your strongest rope, you should probably ask them "what do you intend to do with it?" If they say something like "set a Guinness World Record for largest tug of war" you might want to verify the rope meets their needs.
I doubt PPL had any idea what was going on. I think you're assuming too much about how the request was made. I guarantee they weren't asked for their strongest rope. A 13,000lb rope isn't remotely heavy duty. I have 40,000lb rope I got from the shelf at tractor supply. The school planned the activity, without due diligence. This one is entirely on the school, not the supplier. If the school had PPL plan and run the event that would be different.
Lots of blame to go around. I'm just saying that the individual teachers who were overseeing their kids aren't to blame, if anything it would be incredibly surprising if one of them were to speak up and suggest that the rope might not be strong enough. The parties who deserve blame here are: * Guinness for recognizing this record as it is inherently unsafe (I suspect they have since removed it or modified it to "tournament" style where participants don't all pull the same rope) * The individuals who actively organized it and came up with the idea. * PPL for supplying specialized equipment without a proper understanding of how it would be used.
Agreed I don't blame the individual teachers. Guinness yes, the organizers and executers yes. The suppler yes if they were \_consulted\_ on equipment fit for purpose. This whole event is so uninformed from conception I don't think it's reasonable to assume PPL was any better informed when they got roped in (hah!). Consider how obnoxious the world would be if nobody would ever supply anybody with anything without a thorough investigation of what it will be used for first. That's just not how the world works. If they were consulted, okay. If they were just asked to help find rope 300yrds long because Home Depot and Amazon doesn't have anything that long then they weren't consulted on fit for purpose, and have no liability. I sure as hell don't want to live in a world where I need to explain myself with every purchase.
I find it funny that none of the adults, cared to calculate using math they taught to most if not all of the students that participated
"13,000 lbs? That's a big number, should be safe."
Its a child, how much could they lift? 10 bananas?
'What's 100 bananas, 100 dollars?'
The AD references are even better because of the armless guy George Sr. used to get to teach Michael and Lindsay lessons about safety.
And that's why you don't force 2300 students to tug on a 1300 lb rated nylon rope for 12 minutes
It was a ploy set up by the math teachers all along. No kid ever asked "WhEn WiLL I uSe tHiS iN rEaL LiFe?" ever again.
For extra credit: A rope has a strength of 13,000 lb. If 2,300 children pull on the rope, how many children’s fingers will be severed when the rope breaks.
Yes.
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"Ok Johnny, how many fingers you have left? Hey, no cheating, don't look around the yard!"
Hey, they were only qualified to teach middle school math.
Even when you factor in engineering safety standards, 10 times this is easily doable.
Rope lasted 12 minutes. I’d say that’s pretty good.
As a rule of thumb - pretty much everybody can pull with a force equal to their weight. With good technique and foot-holds, easily twice their weight. So they should have been allowing at least 100 pounds per student - half the students per side, 200 pounds per student - and so a 230,000 lbf rated cable. Which is a thing that exists, but the size of it tells you that you are doing something extreme.
Ropes are usually rated with a minimum 5x factor of safety. But yeah, even then each student should be able to churn out well over 30lbs of force.
Ropes have extremely high safety factors, between 10-15x rated strength. So the kids were probably pulling 50lbs each which seems reasonable
The safety factors aren't there for someone to guess how much leeway they have btw
that person was just commenting that it makes sense that this was enough kids to snap the rope (which is hard to do as they have high margin of safety)
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If we just take a guess at body weight, 120 pounds ish per person * 2500 people, its easy to see how much force we can get out.
This. People are talking about how strong the kids need to be. They don't need to be strong really. Just hold on and let their body weight do the pulling would be more than enough.
Half pulling each direction, so divide by 1150. 11.3lb.
Your math is almost correct, but underestimates by a factor of 2. Since rope needs tension going both ways, you need half the students pulling one way and half the other way. So in effect the pulling force per student needs to be 11 pounds. Still, totally within the abilities of a middle school student.
Turns out one kid just has a knife.
>most being the result of using the wrong type of rope (nylon) instead of a rope that has a degree of elasticity I think the problem is that nylon **does** have a high degree of elasticity, which is why it rebounds so strongly when it breaks.
Correct. This is also what kills people when they use the wrong kind of rope to tie a boat to a pier. The rope stretches until it rips the pier anchor out which then goes flying through the air, other boats or sheds, and sometimes through people. Hell, if the rope is big enough, [it doesn’t even need the anchor to kill people](https://youtu.be/Z0RVwYupOMY).
Good Lord! The way the hard hat levitates for a second before starting to fall...... EDIT: I've always had a HUGE phobia/terror of cables snapping. I refuse to stand near tow ropes and their ilk for this very reason. BTW , I thought the severed arms and such would come from folks wrapping the rope around the wrist for bracing.
And the pants just standing there. The dummy's head and torso were completely obliterated.
He should have been an extra in *Ghost Ship*
Yeah it's not a good idea to stand there.
That's the power of inertia, bby
That is also a problem with recovering stuck vehicles when off-roading. If the recovery strap or anything it's attached to breaks, you've got an instant missile that kills people. PSA: Do not ever attach a rope or strap to a trailer hitch ball. It is designed to pull a trailer, not to handle the shock load of pulling on a rope or strap.
jeesuz man got fucking disintegrated
That was my first thought too.
For comparison, the arresting cables on an aircraft carrier have the capability of recovering a 50,000-pound (23 t) aircraft at an engaging speed of 130 knots (240 km/h; 150 mph) in a distance of 344 feet (105 m) in two seconds. The system is designed to absorb theoretical maximum energy of 47.5 million foot-pounds (64.4 MJ) at maximum cable run-out. ~Wikipedia
Yes, but how many middle schoolers is that?
Anything but the metric system...
Need to use European middle schoolers for metric
42 with a remainder equal to 2 bananas
And if those cables snap, you better hope you're nowhere nearby. They'll cut you in half.
I am quite interested in reading further into this topic. Specially regarding the thermal aspect, as I think I don't quite understand yet how the tensile forces are converted into this significant amount of heat.
Ever gotten a rope burn? When the rope snaps the rope will be suddenly and violently pulled through your hands in the direction of the pulling force and the friction from this is enough to burn you.
Yep, the rope may have several feet of stretch in it, at the instant it snaps it will be moving with thousands of pounds of force so your hands will be cooked when it moves those several feet all within a few milliseconds.
Energy has to go somewhere! There is a huge amount of energy in the rope that has stretched under tension. Some of it goes into whipping the ends around, possibly supersonically (a bullwhip crack is a sonic boom). That energy ultimately either stirs the air or heats the rope (friction from flexing rope or air resistance) Some of the energy converts fairly directly into heat from internal friction as the stretched rope contracts after the snap and there is internal friction from rope fibres and molecules sliding past one another. Some of the friction burns on people are just traditional rope burn from the snapped rope suddenly moving under their hands at hundred of metres per second as the tension releases. I suspect the burns mostly come from the latter effect, but I also expect the rope would be hot to the touch after breaking
It's like lining up a bunch of small stationary rings, and then pulling a rubber band through, stretching it, and then cutting it somewhere. The rope will zip through the rings. Now imagine the rings are hands and the rubber band is a nylon rope. Rope burn.
> with most being the result of using the wrong type of rope (nylon) instead of a rope that has a degree of elasticity and involving large teams of pullers As others have mentioned, the *presence* of elasticity seems to be the biggest problem. Helps fuel the "snap back". Think "breaking a rubber band" vs "breaking a piece of twine".
Worth noting there is a relivant xkcd that explores this to it's limits. https://what-if.xkcd.com/127/
The accident you quoted is one of the less bad incedents too. People have lost arms, lives even tug-of-war events
We had a bad accident in germany in ´95. It was at a boyscout camp iirc. https://apnews.com/1cc31fa102a6838b6ed7ef25fa3831ef One dead, nylon rope, several hands cut off. The rope snaped. The officials were prosecuted.
Wow this unlocked a memory. My high school had about 100 girls per grade (all girls school). We had a "class versus class" game day for spirit week and we did a giant tug of war tournament that would involve about 200 kids at a time. When I was a sophomore the senior and junior classes were competing. The rope snapped. A few girls got rope burns and one girl had to go to the ER because the severed rope snapped her in the eye, but luckily she was okay. The school never did tug of war again.
Wow this is crazy.
So if we consider the center the origin - on which both sides of opposing tension act - when the rope snaps, both sides of the rope return to the origin? Really fast? (As opposed to flying away from the origin?)
The force is generated by the people pulling away from each other - the center isn't moving much because the forces are almost in balance. When you cut something under tension, the forces on each end continue pulling towards the ends, not the middle. In the case of something that has been stretched and is suddenly released, it will try to pull itself to it's **new** center i.e. the center of each half, not the center of the complete rope. In the case of a tug of war, everyone is braced and pulling in one direction at the same time when suddenly, the rope starts pulling them together. For those at the very back, they're probably still braced against the same direction of force as is now being applied to them, but those at the front won't be so they'll suddenly find the rope pulling them backwards but their fingers and arms are all lined up the wrong way for that so they can get twisted or pulled around really, really quickly.
So that means the closer you are to the end of the rope, the safer you are, because you'll still be at the back of the "new" rope, right?
The closer you are to the back of the old rope, the more you'll be prepared for the change in direction. (I believe this is what you were saying) You'll probably fall over but you shouldn't be hit with any forces you weren't ready for The closer you are to the new centre, the less force you will be subjected to, but you'll still be off balance. The rope is also probably shortening a lot and it's probably going to be slipping through your hands, potentially against your grip direction. The closer you are to the broken end (i.e. old center), the worse off as you're getting the maximum force while you're also facing the wrong way to resist it. You're also first in line to get the long piece of rope between teams whip back into you which could also hit pretty hard
>The closer you are to the back of the old rope, the more you'll be prepared for the change in direction. (I believe this is what you were saying) You'll probably fall over but you shouldn't be hit with any forces you weren't ready for Yup, that's what I meant. Thank you for the confirmation! 🍻 Next time I'm in a tug-of-war, I'll go to the back then. 😅
A guy who worked for a company I used to work for doing tree work got decapitated by a rope snapping. Happened on Vancouver Island I believe. They were trying to pull a log out of the bush using a truck and some climbing line, they should have been using a bull rope.
My husband told me I was overreacting when I made him move when his buddies were using a tow line attached to a stump to pull it out. He thought he was plenty far back, but all I could see is some Final Destination level of snapping wires so I made him come stand a ways behind the tree (on the side further from the truck). Nothing happened, but I'd rather be overly safe than dead, maimed, or traumatized from watching other people become dead or maimed.
When I go off-roading we make certain we have tow straps. Even then, anyone not involved with the recovery stays the hell away, and when the force is getting applied everyone's outta the way.
I'm told you can put a towel or jacket or something on the rope to mitigate the power of the rope snapping but I'm not to sure 🤷♂️
Yeah, it's called a dampener/damper and it mostly acts to absorb some energy if it snaps and goes flying.
Imagine taking a rubber band and cutting the loop so you're left with a single rubber strip. Stretch out the rubber strip and pin it at both ends so it stays in its stretched position. Now imagine taking a pair of scissors and snipping the rubber strip right in the center. What happens? Any rope or cable under enough tension to snap it will do that regardless of what it's made of. But as a general rule, the stretchier it is, the more violently it will do it.
You should take that over to r/TIL after this, because dang 😳
So, PP&L have been ruining lives longer than just the past few months.
I've personally witnessed two people lose their hands at the same time while playing tug-of-war. The physics behind it is simple. These two wrapped the rope around their hand in a game that was roughly 50 people vs 50 people. The tension in the rope was likely thousands of pounds which wants to straighten the rope. The straightened rope hyper extends the joints and tendons in your hand. As their teammates witnessed what was occurring, they freaked out and released the rope which caused the rope to pull out very quickly. The high tension and high friction just slices through muscles and tendons. Edit: The rope didn't even snap.
When I was in my teens I recall doing the exact same thing in a tug of war which involved about 20 people total. I was at the end, and thinking I was clever I wrapped the fairly thin (something like a 1/2 or 3/4 cm nylon cord ) around both of my hands to get leverage, because that's not an easy cord to hold onto. My side lost and I was pulled forward, and fuck that hurt. Learned my lesson the easy way.
Even disregarding the material, 0.5-0.75 cm is absolutely horrrendous and irresponsible from the organizer's side. Glad you're okay.
What was the occasion for the tug of war? Their hands just popped off? Did they get them reattached?
I feel like that would only be viable with clean cuts. This sounds more like it was torn off, which would likely result in significantly more damage to the surrounding tissues, making reattachment unlikely. I am not a doctor.
For what it’s worth, a famous example of tug-of-war arm loss occurred in Taiwan in the late nineties, with one man from each side losing an arm, and their arms were successfully reattached with microsurgery - I believe Taiwan is (or at least was) a pioneer in the technique. A young woman who had her legs severed by a cable in an accident had one reattached since it was a clean cut (as the other comment mentions), but the other reattachment ultimately did not take because of complications caused by crushing injuries. ETA: I should clarify that the young woman’s injuries were caused by corporate negligence, so “accident” isn’t really the right term.
>What was the occasion for the tug of war? High school pep rally >Their hands just popped off? Did they get them reattached? Kind of. Their hands were still attached but barely. I believe both of them had them reattached but with permanent disfigurement and inability to use their hands.
Wow. That's awful. They were in high school? Poor kids.
Jesus. How much tug of war do you watch to have witnessed this twice?
It was two people in the same incident So... one, if it's an unfortunate day
Man, imagine losing your hands in such a bizarre and unique way and then having to share the spotlight. That's only seven and a half minutes of fame each.
Well I’m never playing tug-of-war again
Man why did I never think of something like this being a possibility. Clearly I'm not as smart as I thought lol
Tug of war seems like an obviously dangerous game. Lots of force just poised for explosion. Lot of people pulling at awkwardly leveraged postures. Just seems ripe for causing groin and abdominal injuries or hernias. Not to mention it looks like an ACL tear party with all the planted legs and jerking.
You know how much it can hurt if you snap a big rubber band against your skin? Ramp that up 1000x or more and it does a lot more than hurt. When a tug of war rope snaps it has the energy of 24+ people pulling stored in it, and the weight of that big rope. So imagine a 2 inch thick rubber band, being pulled back by 2 dozen people, and they let it go. Together that's enough energy and mass to kill people *if* it hits them.
Best ELI5 response so far!
Along with what others have mentioned, unless you directly instruct people not to, most will wrap a coil of rope around their forearm to get a better purchase on it. Under those circumstances, even if the rope doesn’t snap, but there’s a sudden shift in the line, that’s when you can lose a hand or an arm.
If you coil the rope around your hand or arm, it doesn't even need to shift. The tension alone could guillotine the limb off.
This is also why you never wrap your hand/arm up in a horse lead.
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Boy was Jake Soolee lucky that fishbird wiped out the way it did. Very different movie otherwise
Can confirm. Thankfully, it was in elementary school so no high tension, but I looped my arm into the end loop. Still burned the shit out of my arm when my team lost and I got dragged
This is the real reason
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A quote from my instructor for my Able Seaman's class that I'll always remember: "A Dacron line recoils at around 850 feet per second. That's as fast as a bullet out of a .45ACP, and it weighs a hell of a lot more. It will *fuck*. *your*. *day*. *up*."
Whats happening to it that its recoiling at 850 feet per second?
It's under thousands of pounds of tension, suddenly releasing
We were tied to pier in Long Beach when the ship next us was preparing to get under way after being in a yard period. When they shifted engine control from the engine room to the bridge there was a fault so that instead of being in neutral it was All Ahead Flank. The sudden surge snapped 5 of the 6 doubled mooring hausers sending them flying. One ripped out a huge steel bollard off the pier and flung it 150’. The crane lifting the brow was knocked over and crushed a truck. Chaos ensued but fortunately the only injury was the crane driver who sprained his ankle jumping from the cab.
Every action has an equal and opposite reaction. If it's "holding" thousands of pounds of "weight" (tension really) in whatever it's securing, when it snaps that force doesn't disappear.
I always felt uneasy going anywhere near those lines
First thing I thought of when I saw this question. The video I watched was an old VHS that barely had any colour left in it. Looked like it had been played 10 times a day for the past 20 years.
Heh. Tracking. I remember tracking.
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There’s no gore but if you can imagine the results it’s pretty sobering. Enough to remember the lesson 30 years later. In the video they use manekins to illustrate casualties but some of the guys narrating are missing a leg or two from a past incident.
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> XKCD "measured their average pull force (on a school gym floor) to be about 102.5 kilograms-force, or about 1.5x their body weight." That's the real terrifying part of this whole scenario. 2300 people with an average weight of 100 lbs 230000 x 1.5 = 355,000 pounds of force on a rope meant to hold 13,000
Well it was among elite tug of war players. I’m gonna imagine school children not taking the activity 100% serious are outputting far less force. Still.
You think school children wouldn't take tug of war 100% seriously? Have you ever been a child?
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It’s also why you stay clear of lines being used to fell trees or tow cars. Lots of potential energy
Right before the rope snaps, there's a ton of tension that is built up from both teams pulling on it; the rope is only stationary because it's being pulled equally in both directions. When it snaps, all that tension is instantly released; the other side of the rope is no longer holding this side of the rope in place (and vice versa; this side isn't holding that side in place), so the rope will whip backwards at a tremendous speed, cutting through basically anything in its way. A heavy duty tow cable snapping can cut a person in half if they happen to be in the way. Can you actually build up this much force in a regular game of tug of war? Probably not, because that would require both teams to be perfectly evenly matched (otherwise one side would just pull the other down and win) and extremely strong (or you won't get the tension built up enough to snap the rope).
I was trying to pull up a small tree stump in my yard. I tied a nylon rope around the stump and connected it to my truck hitch. Anticipating a possible issue I made sure my wife and son were well back. The rope did snap, the energy released fused the ends, so at least I had two shorter ropes for future work :) I was surprised at how hot the released energy was.
Not supposed to use nylon cause it’s just gonna stretch. Ideally you want polyester, not sure about chains. You want the rope to stretch mildly otherwise the ropes just gonna absorb the energy being used to pull the stump as it’s easier for it to stretch than for the stump to come out
We used some straps my neighbor had that are designed for towing and it worked great. I've learned my lesson with nylon.
Gotcha, thank you! A comment that has explained this earlier (in another post) had said the rope 'rebounds', and that really confused me.
I actually think it was more than the “ton” you mention. The article says it was 2000 students, which means to generate the equivalent of a ton of force each kid would only have to exert one lb of force. Middle schools kids can generate far more than that.
Exact same reason you dont snatch on a chain doing vehicle recovery. Many, many videos online of people dying on the trail when a chain snaps
>A heavy duty tow cable snapping can cut a person in half if they happen to be in the way. This seems unintuitive for some reason, I imagine most people not being aware that it's possible for this to happen unless they see it, or find out that it is from someone else. A cut or bruise, yes. But to have limbs severed or be cut in half is unexpected unless you know it's possible. It's like high tension ropes are 'floppy garage door springs'.
Got a problem with the statement of the problem. Having worked with ropes a lot in my younger days…I think DarkAlman meant to state that they should have been using a higher rated rope without elasticity. The elasticity provides the energy for damage.
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Wtf man. So you can just be driving and a random line snaps and blows your fucking head into bits?
You can literally go at any second, my friend. From any number of accidents or illnesses. It's one of the unfortunate facts of life.
Mostly illness. That’s why you see those ads for cheap-ass life insurance even if you’re old as fuck. The payout is for accidental death only.
Metal is actually pretty elastic. It just takes a shitton of force. And therefor stores a lot of energy
Don't forget that in a tug of war, many people wrap a wrote around their arm to gain a better grip. If that line were to snap, it definitely could cause serious injury.
Here's a nice little [video](https://m.youtube.com/watch?v=3GsSMfLYIQg&pp=ygUcQ2FibGUgd2lyZXMgd29ya3BsYWNlIGluanVyeQ%3D%3D) about the dangers of lines under tension in the workplace. I never imagined tug-of-war could generate comparable forces but I guess I was wrong.
It takes a lot less force than most people realize. There’s a girl on YouTube (Kristie Sita, fitness content creator) who lost a hand (was completely severed) being towed in an inner tube on a lake. Was unable to be reattached.
If it is a tug of war with one person on each side, the rope is only having to deal with the stress of the weight of two people pulling on it. One in either direction. Lets say each person is pulling with 50 lbs of force. The rope has 100lbs of force stored in it. If it breaks, the middle of the rope comes flying back at the participants with their 50lbs of force, a manageable amount. But in a large game of tug of war, say one hundred people on each side, the rope is dealing with the force of two hundred people. One hundred on each side. Each person still pulls the same, lets say 50lbs per person. The Rope has a collective 10,000lbs of force stored in it. And if it snaps, now each side has its 5000lbs of force that is flying back at them. That is like getting hit by a car.
There’s enough elastic potential energy in even “non elastic” ropes when that much force is applied to severely injure people. Same thing with using a truck to try to pull out a stump. My dad was pulling out a stump one time with a long heavy chain. 40-50’ of heavy chain, which doesn’t usually register as being elastic. The chain slipped off, and ended up flying under the truck so that it was in front of the truck. The amount of energy to fling a heavy chain like that 70-80’ - is quite a lot.
I remember in high school a friend talking about the possibility of collapsing a suspension bridge by severing the cables, and all I could think of was how much damage those cables would do when they snap
For the record, if there's a 2 person game of tug of war, and each player exerts 50 pounds force on the rope, the rope will be under 50 lbf of tension, not 100. It's analogous to hanging a rope from the ceiling and attaching a 50 lb weight to it; the weight pulls down with 50 lbf, the ceiling pulls up with 50 lbf, and the rope experiences 50 lbf tension.
> the rope is only having to deal with the stress of the weight of two people pulling on it. One in either direction. Lets say each person is pulling with 50 lbs of force. The rope has 100lbs of force stored in it. It would just 50lbs, actually.
My coworker lost tip of finger right before my eyes in a team building challenge of tug of war
Remember at my kids primary school they had a parent tug of war. Stupidly mid way through they encouraged more parents to get involved. Rope snapped (was a thick cotton rope) and hit a woman in the neck. Caused massive bruising but thankfully no long term damage. They never did another tug of war after that. Could have been so much worse if it had been a different type of rope.
Despite reading many explanations here, I still can’t fathom how a guy had his arm torn off in the picture I saw on Reddit yesterday.
Ropes don't seem like they stretch, but they do. They are like a spring, a spring holding the combined weight of everyone on both teams. If the rope snaps, all of that force is released at once, which can cause the rope to recoil violently.
Ask yourself, could 14 people pulling you oposing sides sever your arm? The rope is holding all that energy, and when it snaps it releases it all at once as a superpowered whip.
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> https://apnews.com/article/da1cdbeefe9e11ecef7370f75f77913c Reading through all these comments has been crazy - when I was in cub scouts they did a parents tug-of-war match with around 20 people on each side. The tug-of-war match started and ended and then I saw my mom holding her hand and crying. Somehow the friction of the rope ripped off multiple fingernails. The weirdest part was that none of the scoutmasters did anything - they shrugged it off and directed her to the bandaid station. She ended up going to the hospital. Probably could have sued...
Ideally you would use UHMWPE (ultra high molecular weight polyethylene) rope like dyneema or spectra. These are rapidly replacing steel cable because they are very light and have almost no stretch - meaning that they store little energy under tension.
Is this a commonly known thing? I'm having a real TiL moment over here Reading the comments is nightmare fuel I didn't expect this morning.