Talk:Fall factor
What is the original source for the fall factor of 2?
How did people first calculate that a fall factor of 2 is as much as the human body can withstand? I've heard at least one rumor on this issue which is described in this mail I tried to send to snopes.com (but their submission form is broken):
- I'd like to submit a rumor on the origins of the climbing fall factor. The fall factor is the amount of force due to de-acceleration that a human being can tolerate. See e.g. this Wikipedia article on the matter:
- The rumor that I've heard several times in climbing circles is that the original source for what the human body can tolerate in these circumstances are medical experiments performed by the Third Reich in Germany during World War 2.
- However I haven't found anything online supporting this assertion, one paper which I've found which discusses fall factors located here:
- States in its acknowledgements section that:
- "Calculations like these have been published many times over. As best as I can tell, their origin goes back to Belaying the Leader, Richard M. Leonard and Arnold Wexler, Sierra Club Bulletin 31 (1946)"
- It would be interesting if you guys could debunk this and find out what is the original source for how much de-acceleration a human body can tolerate. Did someone do practical experiments on this (like the rumored Third Reich) or is the source derived from calculating how much stress the human skeleton can take or something else entirely?
The sources cited in this article don't give a definite answer to this question, it would be interesting if someone could add them. --Ævar Arnfjörð Bjarmason 16:34, 11 December 2009 (UTC)
Units of variables needed
Please provide the units for the variables used in the equations (F, k, U, m, R, g). A diagram or two would also be useful. —Preceding unsigned comment added by 174.25.59.149 (talk) 06:37, 28 October 2010 (UTC)
Arguments for the new version of December 4, 2010
The last version contained several errors, unclear passages, and uncommon use of variables and expressions:
- Formula for maximum impact force F1: With the spring constant k as it is used in physics, the dependency on the rope length is not correct (when k is defined as Elasticity modulus the dependency on the rope’s cross section is missing).
- The calculation of k with parameters of the UIAA standard fall conditions is not transparent and not correct with respect to the dimensions. A more transparent formula is given with an explanation for its use.
- Used variables such as r for length of rope and l for fall height are uncommon in physics and were replaced. The variable k as modulus of elasticity is not correctly used (see point 1.)
- “Maximum impact force” is usually only called “impact force” by rope manufacturers.
- A section on the deficiencies of the undamped harmonic oscillator model for describing a climbing rope has been added.
- The formula of the impact force when the rope is clipped into several carabiners is cancelled, because 1. no reference is given (the cited reference does not show it), and 2. the situation is not described correctly, e.g. the angles between rope and carabiners for the dry friction are not considered (for the same number of carabiners a zig-zag clipping leads to more dry friction than a straight line clipping).
- The order of chapters has been changed: theory at the beginning, applications at the end.
- The references have been classified according to true references and external links.
- “Category” has been expanded to include physics