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bigtoeski
Sep 22, 2007, 4:58 AM
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I have a question: I have read that to test gear manufacturers will attach an 80 kilo iron block to the end of a rope and let it fall to create a factor 2 fall (something like a 5 foot fall with 2.5 feet of rope out). Wouldn't a greater foce be generated if the fall were 60 feet as opposed to only 5 feet? In the climbing world you are going to be falling greater than 5 feet. The longer the fall the more time you have to accelerate and gain more velocity right? So the testing they do doesn't really represent a real world situation right? I guess my question is: does a 5 foot factor 2 fall generate the same force as a 60 foot factor 2 fall? Seems like the 60 foot factor 2 fall would generate more force on the anchor.
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moose_droppings
Sep 22, 2007, 5:14 AM
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bigtoeski wrote: I have a question: I have read that to test gear manufacturers will attach an 80 kilo iron block to the end of a rope and let it fall to create a factor 2 fall (something like a 5 foot fall with 2.5 feet of rope out). Wouldn't a greater foce be generated if the fall were 60 feet as opposed to only 5 feet? In the climbing world you are going to be falling greater than 5 feet. The longer the fall the more time you have to accelerate and gain more velocity right? So the testing they do doesn't really represent a real world situation right? I guess my question is: does a 5 foot factor 2 fall generate the same force as a 60 foot factor 2 fall? Seems like the 60 foot factor 2 fall would generate more force on the anchor.
With a longer fall you have more rope out which gives more time to slow you, lowering the force.
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rocknice2
Sep 22, 2007, 5:38 AM
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The same max impact force is generated for both a 5 foot or 60 foot FF2. The longer fall will hold that peak force for a longer time.
If you plot it on a graph both will peak at about the same point but the area under the longer fall curve will be greater.
I believe rope tests are done with 2.5 meters not feet.
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jt512
Sep 22, 2007, 5:42 AM
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bigtoeski wrote: I guess my question is: does a 5 foot factor 2 fall generate the same force as a 60 foot factor 2 fall?
As unintuitive as it may seem, the answer is "yes" -- to a good first-approximation, for a given fall factor, maximum impact force is independent of fall length.
The subject has been thoroughly explained by rgold here.
Jay
(This post was edited by jt512 on Sep 22, 2007, 5:45 AM)
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majid_sabet
Sep 22, 2007, 6:31 AM
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let's see
[URL=http://imageshack.us]
[URL=http://imageshack.us]
[URL=http://imageshack.us]
[URL=http://imageshack.us]
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bigtoeski
Sep 22, 2007, 6:35 AM
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Awsome, Thanks for everyone who replied!! And you are correct rocknice it is meters not feet, my mistake.
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