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USnavy
Nov 10, 2007, 1:11 AM
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shockabuku
Nov 10, 2007, 1:18 AM
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What's a force curve (force/time)?
(This post was edited by shockabuku on Nov 10, 2007, 1:20 AM)
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jt512
Nov 10, 2007, 1:27 AM
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rocknice2 wrote: j_ung wrote: jt512 wrote: j_ung wrote: USnavy wrote: It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it. You are confusing force with energy, and consequently your post makes no sense. Jay Me ... several thousand miles ... physics. Thanks for the clarification. j_ung Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended. Another victim of American education? Edit: Apparently, things aren't much better in Canada. Jay
(This post was edited by jt512 on Nov 10, 2007, 1:29 AM)
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greenketch
Nov 10, 2007, 1:29 AM
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USnavy wrote: Was he actually using dynamic climbing ropes in those videos or were they bungee ropes designed for that type of use? The last jump he did looked like it was with a dynamic rope but I am not 100% on that one. Yes, Dan did most of his stuff with Dynamic climbing ropes.
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flint
Nov 11, 2007, 4:48 AM
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flint wrote: Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport. OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5 Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1 This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do... Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope. j- Little bit of a brain fuck up here... Sorry for the harsh and actually wrong post USnavy. I will come and stand in your corner now. I am still ashamed of my passport, but for an all new set of reasons. j-
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trenchdigger
Nov 12, 2007, 5:57 PM
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jt512 wrote: rocknice2 wrote: j_ung wrote: jt512 wrote: j_ung wrote: USnavy wrote: It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it. You are confusing force with energy, and consequently your post makes no sense. Jay Me ... several thousand miles ... physics. Thanks for the clarification. j_ung Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended. Another victim of American education? Edit: Apparently, things aren't much better in Canada. Jay This thread just keeps getting better and better, doesn't it Jay? Yeesh...
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itstoearly
Nov 12, 2007, 6:25 PM
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From my understanding, falling 1 foot on 6 inches of rope and falling 200 feet on 100 feet of rope produces the same *peak* force on the anchor point. If you were to compare the graph of the 2, they would be identical, except that the latter would be stretched out over more time. I would make a graph, but I am busy being lazy.
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skinner
Dec 10, 2007, 4:01 AM
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A person like USnavy comes along and asks an honest question, which if they understood *why* they wouldn't have asked it in the first place. In response he gets ridiculed by Flint, I guess that's the rc.com way huh? With only a few posts USnavy may be new to climbing, but gawd.. they should know and fully understand all this stuff before they dare to post here! It's no wonder there are so many who choose to just lurk. Welcome to rc.com USnavy
(This post was edited by skinner on Dec 10, 2007, 4:14 AM)
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j_ung
Dec 11, 2007, 1:17 PM
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jt512 wrote: rocknice2 wrote: j_ung wrote: jt512 wrote: j_ung wrote: USnavy wrote: It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it. You are confusing force with energy, and consequently your post makes no sense. Jay Me ... several thousand miles ... physics. Thanks for the clarification. j_ung Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended. Another victim of American education? Edit: Apparently, things aren't much better in Canada. Jay I'll take my own lumps, thanks. The American education system doesn't need me dragging it down further.
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lobstertronic
Dec 11, 2007, 3:01 PM
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flint wrote: Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport. OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5 Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1 This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do... Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope. j- The bridge is 59 metres above the ground...
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scottek67
Dec 6, 2009, 4:44 PM
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brokesomeribs wrote: silascl wrote: Your a idiot. Oh, the irony!
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dynosore
Dec 6, 2009, 5:36 PM
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j_ung wrote: USnavy wrote: It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it. No. Hint: ke=1/2mv^2
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dynosore
Dec 6, 2009, 5:41 PM
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zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet.
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sungam
Dec 6, 2009, 5:55 PM
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dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet. Are you trying to imply that the pulley effect isn't real? You're not that stupid, dude. Come on. And, if you're curious, if there is little or no friction between the the pully and the rope then there is a total of 250lbs hanging on that pully. 125 pounds from the deer, and 125 from whatever the other end of the rope is tied to. (we're ignoring the angles, here). Think about it - if the deer was exerting 125 pounds on one end of the rope and nothing was pulling on the other, the rope would run through the pully and the deer would fall, right? and since both the weight of the deer and the pull from what the rope is tied to are downwards, that means the downwards force on the pully is the sum of those two. 125+125=250 lbs of downwards force.
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jt512
Dec 6, 2009, 6:01 PM
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sungam wrote: dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet. Are you trying to imply that the pulley effect isn't real? You're not that stupid, dude. Come on. He's had two years to think about it. Jay
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sungam
Dec 6, 2009, 6:06 PM
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jt512 wrote: sungam wrote: dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet. Are you trying to imply that the pulley effect isn't real? You're not that stupid, dude. Come on. He's had two years to think about it. Jay Damn, I didn't notice how old the thread was. The post I qouted, however, was made today. Fricken zombie threads.
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milesenoell
Dec 6, 2009, 6:15 PM
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dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. This is one of the best examples you could have thrown out for two reasons. 1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design. 2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up.
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sungam
Dec 6, 2009, 6:18 PM
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milesenoell wrote: dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. This is one of the best examples you could have thrown out for two reasons. 1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design. 2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up. Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds.
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giza
Dec 6, 2009, 6:29 PM
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skinner wrote: A person like USnavy comes along and asks an honest question, which if they understood *why* they wouldn't have asked it in the first place. In response he gets ridiculed by Flint, I guess that's the rc.com way huh? With only a few posts USnavy may be new to climbing, but gawd.. they should know and fully understand all this stuff before they dare to post here! It's no wonder there are so many who choose to just lurk. Welcome to rc.com USnavy Agreed. This is not a forum to be inquiring about legitimate climbing-related topics. It's the arena of douchebag spraylords where every post will be scrutinized and torn apart not only for its content but also its spelling, grammar, the poster's # of posts, etc. There are plenty of other forums where your question would be answered from a place of knowledge and mutual respect.
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milesenoell
Dec 6, 2009, 8:40 PM
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sungam wrote: milesenoell wrote: dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. This is one of the best examples you could have thrown out for two reasons. 1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design. 2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up. Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds. Not if the rope is tied to itself or back to the deer (as I had presumed). I was assuming that he could tell the difference between a 63 lb and a 125 lb deer. (and a 63 pound deer would be so runty he probably wouldn't be posting about it.)
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sungam
Dec 6, 2009, 8:47 PM
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milesenoell wrote: sungam wrote: milesenoell wrote: dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. This is one of the best examples you could have thrown out for two reasons. 1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design. 2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up. Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds. Not if the rope is tied to itself or back to the deer (as I had presumed). I was assuming that he could tell the difference between a 63 lb and a 125 lb deer. (and a 63 pound deer would be so runty he probably wouldn't be posting about it.) I suppose. I didn't think about it since I've never seen a 70 pound or a 125 pound deer hanging from a pully so...
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milesenoell
Dec 6, 2009, 8:50 PM
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giza wrote: There are plenty of other forums where your question would be answered from a place of knowledge and mutual respect. But where's the fun in that? edited to add: Oh, I didn't realize this thread was in The Lab. Sorry if I've come off as snarky.
(This post was edited by milesenoell on Dec 6, 2009, 8:54 PM)
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Adk
Dec 7, 2009, 12:41 AM
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sungam wrote: milesenoell wrote: sungam wrote: milesenoell wrote: dynosore wrote: zealotnoob wrote: OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it... So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. This is one of the best examples you could have thrown out for two reasons. 1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design. 2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up. Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds. Not if the rope is tied to itself or back to the deer (as I had presumed). I was assuming that he could tell the difference between a 63 lb and a 125 lb deer. (and a 63 pound deer would be so runty he probably wouldn't be posting about it.) I suppose. I didn't think about it since I've never seen a 70 pound or a 125 pound deer hanging from a pully so... He might be posting about it. Ya see. There are briefcase deer ---- < 50 lbs suitcase deer------ >50 < 100 lbs Backpack deer ----- >100< 140 lbs one man drag deer-->140<200 lbs two man draggers > 200 lbs the force that any of them exhibit on a pully is not that hard to figure out. If math is tough think of it this way. If you have a backpack deer (you can actually wear it like a backpack) and you weigh the same and you try to lift it off the ground you can't. If you are a bit heavier you still can't because of friction at the pully. If for some reason you can get it in the air and you both neither go up or down you have how many pounds hanging from the pully now? For now don't think friction at the pully. See where I'm going? Tie that off and you have how many pounds on the deer side of the pully and how many at the tie off point? How many are at the pully? Briefcase deer do taste pretty good.
(This post was edited by Adk on Dec 7, 2009, 12:48 AM)
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adatesman
Dec 7, 2009, 2:43 AM
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