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18633 clicks; posted to Main » on 25 Mar 2013 at 8:08 PM (4 years ago)   |   Favorite    |   share:    more»

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ZeroPly: Mithiwithi: More likely he measured, say, 135 feet of rope on the ground and failed to account for it stretching by more than 5 feet under load.

Still, ouch.

135 feet of dynamic kernmantle can stretch about 20% under load, which would be an additional 27 feet. Generally that happens only on a long lead fall. But on a swing, the initial shock loading while not perceptible might still stretch it significantly, from which it won't recover during the entire arc.

PSA:  Climbing rope is for climbers, so please stay the f*ck away from it if you don't know how it behaves. Gravity behaves differently on the wall than it does in Mountain Dew commercials.

I would only have used climbing ropes to lead the climb up. Then get out the fat ass static line outta the bag.

As a math teacher here in Utah I can proudly say that was not my student.

/not that I teach the physics of rope, but still

Pvt Joker: meyerkev: largedon: As a math teacher I look forward to using this story the next time some smart ass kid asks me why he needs to learn math.

Of course, if Mithiwithi is right, they really need to learn physics.

/Namely, conservation of energy as applies to springs
// .5m(h + l)^2 = .5kh^2  Solve for h, where l is the length of the rope and h is the additional height needed to stop falling.
///  If l + h > 140 feet, you will DIE.

What's on the left side of the equation? Shouldn't it be the potential energy due to gravity, m * g * h?

Yes.  I'm an idiot.  Remembered 1/2mv^2 as energy and plugged in h instead of v.

mg(h+l) = .5kh^2

/5 years since AP Physics.

I had something slightly similar happen to me once. Good thing, it was from a bridge over the American River and only about a twenty foot drop. Still, that whole "rope stretches under load" deal can be a real biatch.

YODO

Wow- look at all the arch comments.

Ahem...

Please please please don't mess with rare stone formations. You'll farking break it one of these days and we lose the rare novelty.

meyerkev: Pvt Joker: meyerkev: largedon: As a math teacher I look forward to using this story the next time some smart ass kid asks me why he needs to learn math.

Of course, if Mithiwithi is right, they really need to learn physics.

/Namely, conservation of energy as applies to springs
// .5m(h + l)^2 = .5kh^2  Solve for h, where l is the length of the rope and h is the additional height needed to stop falling.
///  If l + h > 140 feet, you will DIE.

What's on the left side of the equation? Shouldn't it be the potential energy due to gravity, m * g * h?

Yes.  I'm an idiot.  Remembered 1/2mv^2 as energy and plugged in h instead of v.

mg(h+l) = .5kh^2

/5 years since AP Physics.

It would also be interesting to see how rope behaves compared to an ideal spring.

/ 18 years since AP Physics.

I'm loving it.

skantea: Measure twice, jump once...

*shakes tiny tape measure*

LesserEvil: Bastard Toadflax: It turned out Utah was his [puts on sunglasses]...

arch enemy.

Yeeeeeeaaahhh!

That deserves a picture....

[wtflolomgbbq.no-ip.org:88 image 600x338]

Is he about to put on a second pair of sunglasses? Or did he decide to take off the second, superfluous pair?

/so confused.

Pvt Joker: meyerkev: Pvt Joker: meyerkev: largedon: As a math teacher I look forward to using this story the next time some smart ass kid asks me why he needs to learn math.

Of course, if Mithiwithi is right, they really need to learn physics.

/Namely, conservation of energy as applies to springs
// .5m(h + l)^2 = .5kh^2  Solve for h, where l is the length of the rope and h is the additional height needed to stop falling.
///  If l + h > 140 feet, you will DIE.

What's on the left side of the equation? Shouldn't it be the potential energy due to gravity, m * g * h?

Yes.  I'm an idiot.  Remembered 1/2mv^2 as energy and plugged in h instead of v.

mg(h+l) = .5kh^2

/5 years since AP Physics.

It would also be interesting to see how rope behaves compared to an ideal spring.

/ 18 years since AP Physics.

recovery is orders of magnitude slower because there's so much friction inherent in the way the rope is constructed. Initial stretch is much like an ideal spring, but in recovery , all the energy gets absorbed back into coiling the fibers together, so no boioioioioioioing action. Huge dampening effect.

I guess you could say he was at the... (puts on sunglasses)
end of his rope.
/Yeeahhhhh

Yoiks! And AWAY!

I bet that left a mark.

half eaten oreo: Will you marry me?

Came for this, leaving satisfied.

ZeroPly:PSA:  Climbing rope is for climbers, so please stay the f*ck away from it if you don't know how it behaves. Gravity behaves differently on the wall than it does in Mountain Dew commercials.

But teh interwebs...!

I love this rope thread so much.

Bastard Toadflax: LesserEvil: Bastard Toadflax: It turned out Utah was his [puts on sunglasses]...

arch enemy.

Yeeeeeeaaahhh!

That deserves a picture....

[wtflolomgbbq.no-ip.org:88 image 600x338]

Is he about to put on a second pair of sunglasses? Or did he decide to take off the second, superfluous pair?

/so confused.

I think he's just...
*puts on sunglasses*
putting you on.

Yyyyeeeeeeeaaaaaaahhhhh!!!"

Not knowing how to measure seems to be a common problem with people who want to do things like this.

I bet they measured the rope so it would be slightly above ground without taking into consideration his body weight. As soon as he jumped the rope probably stretched a couple feet.

Am I the only one that read the headline and thought "no, 280 minimum of rope" because swings have two runs?  Yes, lame ones might be single-run but fun ones are dual so you may <i>swing</i> up to height!

Sure, measure said medium under load and determine the maximum stretch before testing.  In fact, test with a known 'false' hard desk (I love Top Gun) and then do the real jump once you know what the fuk you are dealing with.

I hate idiots.

Its strange, because one would presume that when attempted this stunt one, you know, kinda makes sure to measure the rope right.... Practically seems like THE most important part of said stunt.

Go Pro Zero, for those who can't do math.

Reminded me of this; pops So close Mr. Darwin.

Hector Remarkable: There'll be no math in the grave for ye.

'Ere lies the bones of Seamus McGee, who encountered fate at a considerable velocity.

He ditched math.

Measure with a micrometer. Mark with chalk. Cut with an axe.

Yeah, this happened a long time ago when I lived up  near Reno and bungee jumping was the big fad. A guy did the jump off a billboard and wound up with a fractured pelvis and a few broken vertebrae. Turned out what he'd done was carefully measured the distance from the top to the ground, carefully measured the length of his bungee cords, tied off and jumped---forgetting the idea was that the things would stretch quite a bit.

65' and he's lucky he didn't die.

darklingscribe: You'd think that someone would have a bright idea to maybe attach a rock to the end of the rope to test it's length before throwing their body over the cliff.

This. Plus, the rock could help answer critical questions like "Once I clear the ground, am I going to smash into the arch on the return trip?" Bah.

ZeroPly: Mithiwithi: More likely he measured, say, 135 feet of rope on the ground and failed to account for it stretching by more than 5 feet under load.

Still, ouch.

135 feet of dynamic kernmantle can stretch about 20% under load, which would be an additional 27 feet. Generally that happens only on a long lead fall. But on a swing, the initial shock loading while not perceptible might still stretch it significantly, from which it won't recover during the entire arc.

PSA:  Climbing rope is for climbers, so please stay the f*ck away from it if you don't know how it behaves. Gravity behaves differently on the wall than it does in Mountain Dew commercials.

Just what I was thinking - climbing rope. Whoops.

You can't fix stupid.

This thread is making me rethink my jet pack and roller skate combo idea.

Theory Of Null: I bet they measured the rope so it would be slightly above ground without taking into consideration his body weight. As soon as he jumped the rope probably stretched a couple feet.

I was thinking that even if they measured it correctly so that after stretching it would still be short enough, he might not have taken his height into account, since he'd be 5-6 feet lower than the end of the rope.

DogLee: You can't fix stupid.

True. Darwin fixed it for him.

My main concern is the number of shiats who will be climbing such a beautiful and fragile object... its farking sandstone.

People start pissing on top or dumping beer and its gonna take damage.   It IS a transient natural monument to erosion but come on, do you idiots do jumping jacks in any flower bed that you find?

Why is it that Fark does not yet have a "Darwin" tag?  Other than making a couple other tags obsolete I mean...

kevinboehm: Why is it that Fark does not yet have a "Darwin" tag?  Other than making a couple other tags obsolete I mean...

I second this, but imagine how often people would get it wrong. Kind of like the Ironic tag.

I heard the last thing he said before he leapt was, "Dude! Check this out!"

Pribar: Dunno what would be worse Dying quick or living like this dude (NSF lunch or squeamish)

Am I evil for laughing at that?

/ GeronimOHSHIIIIIIAAAAAATTTTTTTTT

Came to post that.  Except they hit the ground on purpose.

Good.  It's dickheads like this that ruin great areas like Moab.

Smeggy Smurf: [cdn-static.denofgeek.com image 300x225]

Is that sonny bono?

Many amusement parks have similar giant swings. Probably will cost \$20 to ride, and it's not beautiful and amazing as that arch, but it's safer and the same thrill.

(go to youtube and search "amusement park giant swing")

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