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jt512
Oct 9, 2008, 3:08 AM
Post #26 of 28
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Registered: Apr 12, 2001
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mtnrock wrote: ...unless theres a way buy using the impact force of the rope to find the spring constant(also shows how streachy the rope is)
I already answered the question. Look back at my posts, and look at equation (11) in rgold's paper.
Jay
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petsfed
Oct 9, 2008, 3:18 AM
Post #27 of 28
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Registered: Sep 25, 2002
Posts: 8599
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mtnrock wrote: o got it. yea it was when i was finding an equation to find the force generated on the peace of equipment the one unknown i was missing was the spring constant but im just going to test for that on my rope unless theres a way buy using the impact force of the rope to find the spring constant(also shows how streachy the rope is)
Read Jay's post. Rinse and repeat.
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petsfed
Oct 9, 2008, 3:37 AM
Post #28 of 28
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Registered: Sep 25, 2002
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jt512 wrote: petsfed wrote: jt512 wrote: petsfed wrote: rgold wrote: Petsfed, there isn't a mathematical model in the world that incorporates every detail of the reality being modeled. If one did, it would in some sense be the reality and not a model of it. Perhaps the essential ingredient in every model is the fact that it ignores details, so your criticism is in fact a foregone conclusion. I'd love to see your model incorporating the mass of the rope, and I would be interested to see, after the mass is properly taken into account, how much effect it actually has on the results. Please do post up. Its supposed to be too cold to climb this weekend, so I'll work on it. I'd expect that for a UIAA rope test, its pretty minor, but if you've got 100 feet of rope out, it might be pretty big (on the order of 5 or 10 percent difference). I'll try to work up some general equations and explanatory assumptions. 100 feet of rope weighs about 3 lb. I'm going to go out on a limb and say that rope mass can be ignored. Jay You're right, it is pretty negligible, but the more rope you have out, the more measurable an affect it will have on the overall system. If you have all 200 feet out, that's nearly 10% of the UIAA test mass. Less than 5%, unless I made an arithmetic error. Jay
Oh, duh. Its 2.2lbs to the kg, not the other way around. My bad. Yeah, around 2%.
Still, if I'm gonna be neurotic enough to actually develop the equations, I'm gonna toss in the little mitigating circumstances.
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