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patto
Feb 18, 2008, 6:03 PM
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petsfed wrote: philbox wrote: Hey jt, is there ever a need to state that there is deceleration as opposed to the word acceleration when considering the forces involved with stopping a climbers fall. Would not deceleration be a better descriptive word? I know that when a climber is initially falling then acceleration would be the best term to use but when a belayer applies a frictional force to the rope would not the climber then be decelerating. The only reason I've seen terminology used like that is to explicitly state the vector direction of the acceleration in terms of the velocity. That is, in acceleration, the force vector is parallel to the velocity vector, whereas in deceleration the force vector is antiparallel to the velocity vector. In common usage, I've found that deceleration implies that when the velocity equals zero, the force also becomes zero. That is, a car is said to decelerate if, after its velocity reaches zero, it does not start going in the opposite direction. But that's just from reading waaay too many physics textbooks.
Truth be told 'acceleration/deceleration' are meaningless without the direction being specified. However in the absense a specified direction there is normally an implied direction. In this case downwards.
Deceleration is normally used when somethings SPEED decreases. Notice I say SPEED and not velocity, there is a difference! This leads to the point petsfed made.
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armsrforclimbing
Feb 18, 2008, 7:15 PM
Post #52 of 72
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Is it time for the same old physics discussion again? In all fairness the Americans in the forum were brought up with a godawful confusing english system of units. There seems to be endless confusion over the KN vs. lbs force vs. lbs mass. That tends to be a speed bump along the way to understanding the only real physics behind fall forces (and the slug is the key to understanding the difference). JT stated his point clearly and concisely. I understand both the confusion, and the frustration that people experience after explaining the physics for the fifteenth time.
I suggest a small compilation of climbing physics available on the main page. It should be heavy on pictures and simplified explanations so to ERASE all the confusion and future questions. Then, and only then, can we elevate our discussions to what constitutes REAL climbing.
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armsrforclimbing
Feb 18, 2008, 7:21 PM
Post #53 of 72
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Oh, and this Majid guy LOVES to argue. Doesn't matter about what, he'll even pick up a small point and expand on that making it the focus of the discussion (i.e. this mumbo jumbo about climbing standards.) I'll cut this short and say that, no, there is no standard in the sense that you are talking about Majid. Nor is there the infrastructure or financing to enforce one, or any interest among climbers.
But I continue to be amused by nearly all of your posts, so don't stop.
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majid_sabet
Feb 18, 2008, 8:09 PM
Post #54 of 72
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armsrforclimbing wrote: Oh, and this Majid guy LOVES to argue. Doesn't matter about what, he'll even pick up a small point and expand on that making it the focus of the discussion (i.e. this mumbo jumbo about climbing standards.) I'll cut this short and say that, no, there is no standard in the sense that you are talking about Majid. Nor is there the infrastructure or financing to enforce one, or any interest among climbers. But I continue to be amused by nearly all of your posts, so don't stop.
A lot of people talk big mouth round here and they act like they know but as soon you ask about a fact, they take 5th.Off course I know these climbing standards do not exist. I had been doing research on this topic for the past eight years but I hoping someone could proof me wrong with solid facts. Anyway, philbox and your reply were the closest and most logical answers that anyone could offer on this topic.
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Dry_Hands
Feb 18, 2008, 8:42 PM
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If gear was rated with no margin of safety, it would be ruined after 1 cycle. Therefore, big wall climbers would have to carry extra gear to replace everthing they "broke" during a climb. With a margin of safety gear becomes a durable good, rather then a consumable.
And, if that's not OBVIOUS enough to the OP...
Even when standards are created and regulated (look at transportation regulation) they typically only test for extreme circumstances beyond which anyone PLANS to use them. I didn't buy a car to crash it at 35mph several times...but if it'll handle that once without killing me...it'll probably handle the potholes around Detroit for 8-12 years and keep me alive through 3 or 6 fender benders (and has).
Climbing gear simply follows a similar pattern of (self) regulation and standardization that they've come up with over the years to satisfy consumers and manufacturers.
By the way...excellent hijack of your own thread...
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philbox
Moderator
Feb 18, 2008, 10:34 PM
Post #56 of 72
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hugepedro wrote: Phil, you make a good point, those would be de facto standards, eh? majid_sabet wrote: I do have a point . THERE ARE NO STANDARDS IN CLIMBING. Please reply when you find some standards for me. That's not a point, that just a statement, the proper response to which is, so what? Now if you can give a reasonably interesting answer to the "so what" question than you might have a point. Otherwise this thread is . . . pointless.
I agree with hugepedro, I think he has put the answer succinctly in his "so what" statement. So there aren't any standards, so what. So governments or official sanctioning bodies have not got any standards to enforce upon us, so what.
The fact that there are no standards have not held the recreation of climbing back from going forward with innovation and safety. We are not seeing huge numbers of people dieing due to failing gear. Anecdotally there appears to be no greater numbers of climbers dieing from pilot error. We have free access in a very timely manner to information in regards to those who do commit pilot error and take the plummet. This should continue to be the case. Any level of official interference with that information stream will increase our level of risk and in fact may lead to increased levels of pilot error.
We don't indulge in the blame game within our chosen recreation as happens within the OH&S of industry. We are all intent on exploring what went wrong and then applying the lessons to increase our own levels of safety.
It is a "change for the future not blame for the past" type of philosophy that we follow. OH&S could learn from us if they really were interested in developing a safer culture within industry.
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jt512
Feb 18, 2008, 11:44 PM
Post #57 of 72
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philbox wrote: Hey jt, is there ever a need to state that there is deceleration as opposed to the word acceleration when considering the forces involved with stopping a climbers fall. Would not deceleration be a better descriptive word? I know that when a climber is initially falling then acceleration would be the best term to use but when a belayer applies a frictional force to the rope would not the climber then be decelerating. Just trying to get my terminology correct and I would love to hear your opinion on this. I have used the term deceleration in the past and am wondering if I have been in error.
In everyday speech it might be clearer to say "deceleration" when you are referring to a stopping a climber, but in trying to explain the underlying physics, the term "deceleration" just confuses the issue, because then one would sometimes have to say "force = mass x deceleration" and sometimes "force = mass x acceleration." Then what do you say if the force you are talking about is actually the net force of an accelerating force and a decelerating force? Or what do you say when you are talking about a force that doesn't change the speed of the object at all, but merely changes its direction? A change of direction with unchanged speed is still an acceleration. Why? Because acceleration is change in velocity, and velocity is a vector quantity, a quantity with two properties, magnitude an direction. If acceleration is change in velocity, and direction is a property of velocity, and a force changes that property, then that force has changed that velocity, and has hence caused an acceleration. So, I think it is actually much better to understand the underlying physical principles, namely, the definitions of force, acceleration, and velocity, and the relationship between them, namely F = ma, than to think of deceleration as something physically different than acceleration.
Jay
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philbox
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Feb 18, 2008, 11:51 PM
Post #58 of 72
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Thanks Jay, very clear and concise.
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evanwish
Feb 19, 2008, 3:53 AM
Post #59 of 72
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our local gym has carabs up to 72kN
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blondgecko
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Feb 19, 2008, 5:24 AM
Post #61 of 72
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jt512 wrote: d1r73 wrote: And yet we still hear of gear failures. I know I have heard of biners snapping on slacklines, harnesses failing, cams breaking, ropes snapping... etc etc I will give you that most of this was probably improper use and/or excessive wear and tear, but mfg know this shit happens and therefore build to account for a certain degree of stupidity/cheapness/laziness/misuses by the users. Also it's nice to have gear that is OBVIOUSLY way too worn to be using before it fails structurally. Harnesses failing? Ropes "snapping?" Where else but rc.com can you get quality misinformation like this! Jay
Well, there is at least one incident that I know of. At Mt Arapiles a few years back, a guy took a whip off Muldoon (13) that quickly turned into a 40m-odd plummet onto the scree slope below when his rope snapped. Apparently it jammed solid over a feature about a metre or so from his harness, and just... snapped, clean off.
It was kinda a celebrity case for a while around Victoria, not just because of the unusual circumstances, but because he walked (well, hobbled) away with not much more than a broken ankle.
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jmvc
Feb 19, 2008, 11:44 AM
Post #62 of 72
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jt512 wrote: jmvc wrote: jt512 wrote: dobson wrote: In reply to: kN is just a unit of force, just as the pound is. 1 kN = 225 lb (approximately). Pounds (lb) are not a unit of force, they're a unit of weight; mass*g. These threads are so predictable. F = ma. Let a = g. Then F = mg = w. Thus weight is a force. Jay Yup, but mass is not, and dobson was talking about mass. You measure wheight in newtons, not lbs. Not important anyway, I'm sure we all understood what you meant, I just had to be a pedant  If you're going to be pedantic, you should avoid being wrong. dobson clearly stated that pounds are a "unit of weight". And the pound is most certainly a unit of force. Jay
Correct on both counts. This is what comes of speed reading and slightly drunk posting..
My apologies for such a brainless post.
Ps. Having used almost exclusively SI units it was news for me that the pound was also a measure of force..
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Dry_Hands
Feb 19, 2008, 2:14 PM
Post #63 of 72
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philbox wrote: evanwish wrote: our local gym has carabs up to 72kN Definite overkill. Those things must be made out of 3/4 inch steel.
I would consider this a hasty judgment. While I agree that the rating is higher then the carabiner will ever be subjected to...keep in mind, it's probably an economic decision to purchase steel. It's likely they would be replacing aluminum carabiners due to wear on hangers, from rope, or anchor chain so often it would be more expensive to buy and maintain something that was designed to be lightweight.
A rating is just a one aspect of a product.
...also, if it was 3/4in steel, it would be way higher then 72kN. I'd guess 5-10 times higher.
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d1r73
Feb 19, 2008, 2:28 PM
Post #64 of 72
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Harness failure
http://www.allclimbing.com/...nt-on-leaning-tower/
Rope Failure
http://www.supertopo.com/...6553&f=0&b=0
http://www.bdel.com/...kage%20-%20final.pdf
Hangers
http://www.supertopo.com/...msg=531266#msg531266
Jay, I was trying to say people do not always maintain/use their equipment well; therefore, it may not be bad a thing that climbing equipment is overbuilt. I do not do any equipment testing, and I have, at best, a high school understanding of physics. I just know that aluminum has a stress cycle, a harness has failed, nylon has burned through nylon, bolts have snapped, people have gotten acid on their ropes and other things have happened that lead me to the conclusion that the current safety standards more than reasonable and not overkill. I was trying to answer Majid's question, and I poorly worded my initial response. I apologize if it seemed as if I was implying that our crags are blood baths filled with dead bodies from ropes and harnesses "snapping". I understand, now, that I should not have used snapped to describe rope failures from chemicals or other sawing/cutting.
(This post was edited by d1r73 on Feb 19, 2008, 9:43 PM)
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Valarc
Feb 19, 2008, 4:19 PM
Post #65 of 72
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jt512 wrote: If you're going to be pedantic, you should avoid being wrong. dobson clearly stated that pounds are a "unit of weight". And the pound is most certainly a unit of force. Jay
This always comes up in these threads. Weight is the force of gravity acting on a given mass. Therefore the units of weight are the same as the units of force. Weight is simply one of many forces. So, saying pounds are a unit of force is the same as saying pounds are a unit of weight.
Where things get really FUBAR is when engineers get involved. Engineers ALSO use pounds as a unit of mass. Worse yet, they rarely differentiate between the two by using the more accurate lbf and lbm (pounds force and pounds mass) to keep things clear, and you're left using context to figure out what they mean.
You can say "200 pounds is roughly equal to 90 kilograms" and 99.9% of people won't blink an eye. What you're REALLY saying, though, is that an object that exerts a 200 pound force downward when acted upon by Earth's gravitational field has a mass of 90 kilograms. Since most people only live on the surface of the planet, you can usually get away with being a bit cavalier about your units. On the surface of the planet, there is a linear relationship between mass and weight - if you know one, you know the other.
For those still confused, think of your bathroom scale. You step on your scale, and it tells you that you weigh 150 pounds. If you took that same scale to the Moon, you would be told you weigh about 25 pounds. Your mass obviously hasn't changed, but your weight has, because the gravitational field on the moon is weaker. If you took the same measurements using a mass balance, instead of a spring scale, you would find that you are about 70 kilograms in either instance. A spring scale measures force, while a balance measures mass.
These threads always remind me of when, during my physics undergraduate days, I was forced to take an engineering thermodynamics course. At one point during this course, we were using the annoyingly awful pounds mass unit. Of course, when you use this unit to do any actual PHYSICS, you have to convert it into a real mass so you can carry out the calculations. You do this by dividing by 32, which is the acceleration due to the force of gravity at the surface of the Earth. However, this damned engineering professor insisted it was a "unitless conversion factor" and had nothing to do with gravity.
If this is how these things are taught at institutions of higher education, it's no wonder why the general population doesn't know the difference. It's only by being completely methodical with these things that engineers are able to build bridges without them falling over.
Oh, did I mention that sometimes kilograms are used as a unit of force? I really wish people would standardize on their damn units and stop confusing the shit out of everyone. It's bad enough the US hasn't switched to Metric, but people are even screwing up the metric system with this nonsense.
(edited to correct a stupid terminology error)
(This post was edited by Valarc on Feb 19, 2008, 4:25 PM)
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Valarc
Feb 19, 2008, 4:23 PM
Post #66 of 72
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jmvc wrote: Ps. Having used almost exclusively SI units it was news for me that the pound was also a measure of force..
The pound is PRIMARILY a unit of force. It is only in (unfortunately all-too-common) sloppy usage that it's used as a mass. The proper "English system" unit of mass is the slug.
To re-iterate, weight = force. NOT mass!
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cchildre
Feb 19, 2008, 4:23 PM
Post #67 of 72
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jt512 wrote: d1r73 wrote: And yet we still hear of gear failures. I know I have heard of biners snapping on slacklines, harnesses failing, cams breaking, ropes snapping... etc etc I will give you that most of this was probably improper use and/or excessive wear and tear, but mfg know this shit happens and therefore build to account for a certain degree of stupidity/cheapness/laziness/misuses by the users. Also it's nice to have gear that is OBVIOUSLY way too worn to be using before it fails structurally. Harnesses failing? Ropes "snapping?" Where else but rc.com can you get quality misinformation like this! Jay
Trophy, since I read it and thought exactly the same. I don't think we have a single certifiable account of a rope snapping. A cut rope, yes, but one snapping from the wieght of a fall, I don't think this has occoured yet.
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Dry_Hands
Mar 18, 2008, 3:12 AM
Post #68 of 72
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majid_sabet wrote: If a falling climber can't generate above 7 kn or 9 kn then why build climbing biners with 24 to 36 kn, cams to go up to 18 kn or other equipment that is rated 2-5 times more than what we could produce during a fall. Why waste so much money and material building something that is way above our maximum falling forces? Does safety factor or potential lawsuits have anything to do with this ?
http://web.mit.edu/...gue_Presentation.pdf
Allows for multiple loadings below the maximum load. According to the work done by these MIT guys, it'll allow a biner to be cycled hundreds of times...costing you about a penny each fall before retirement. If it broke after 2 falls (because they made them only handle 10kn), it would cost you $10/fall.
So you FAIL.
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curt
Mar 18, 2008, 3:24 AM
Post #69 of 72
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majid_sabet wrote: If a falling climber can't generate above 7 kn or 9 kn then why build climbing biners with 24 to 36 kn, cams to go up to 18 kn or other equipment that is rated 2-5 times more than what we could produce during a fall...
Because the industry wants repeat customers.
Curt
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deltav
Mar 18, 2008, 5:13 AM
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While it does seem like over kill, I do feel better knowing that the shit would have to hit the fan before I even come close to maxing the stuff out. Although a fall that generates 11kn would kill you. The human body could not withstand it.
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jamincan
Mar 18, 2008, 3:29 PM
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majid_sabet wrote: hugepedro wrote: Yes, I just told you one standard, did you not read my post? Have you never heard of the EN standards? Or the UIAA? A standard for how to jumar? That's like asking if there is a standard for how to turn on a light switch. A standard for what belay device you must use? Why would there be? But next time you pick up your belay device note the little "CE" stamp on it. That is a standard. Every single piece of gear on your rack complies with a "well documented and approved" standard. CE, EU , UIAA, etc qualifies climbing equipment and set requirements for such qualifications. Standards are sets of protocols that must be followed for certain equipment. For example, UL sets qualification for electrical equipment sold in USA. This means that a light bulb must meet certain requirements to be qualify as a light bulb . The department of urban and hosing sets standards so the particular light bulb must be installed in whatever ways in a residential housing. When a biner is made in Europe, to market such product, the biner must meet certine requirement and UIAA is one of the agencies that qualifies such equpiment. UIAA does not tell what to use when climbing. Climbing standard means that some agency ( not privet club or NGOs, NPOs) enforces a set of minimum requirement related to particular part in climbing.An example would be like an agencies says" To rappel, you must use whatever in such format and this is how it is done". in USA, the military and some of the fire, rescue agencies are the closest group of people who have partial standards but not on everything. As far as I know, there are no climbing standards that specifies how to climb or what to use when climbing.John Long's book ain't standard in anchor set up. Petzl drawing and the Mountaineering 5th addition are not standards and AAC for sure does not set standards on climbing. Is fig 8 the official standard for knot on TR ? Is Grigri the standard for big wall belay ? The 17" tire on a SUV is pretty standard and approved by DOT. You changed that to a 19" and you are SOL with nothing to back you up once you roll you car. Some one help the brother and show me some standards in climbing ( not standards in climbing equipment) .A well documented piece of standard that has been approved by an agency about climbing.
I can't think of many examples where the 'how' of the activity is regulated, certainly not in outdoor recreation anyway. What standards are there for kayaking, for canoeing, for hiking etc?
Governments generally steer clear of regulating recreational activities except in situations of public safety. Outside of government, there is really no way to develop a standard that has any more significance than what Freedom of the Hills tells us.
As an aside, check out the Edmonton section of the Alpine Club of Canada. They have a database of climbing accidents across Canada, as well as analysis into what contributed to the accident.
http://alpineclub-edm.org/accidents/causes.asp
(This post was edited by jamincan on Mar 18, 2008, 3:30 PM)
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mecalekahi-mekahidyho
Mar 19, 2008, 2:28 AM
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So if force x mass = acceleration and mass x acceleration = the right kn rating, then it is logical to say that a kn rating of 1 is = to the force applied when you reach a kn rating of 2. and so on. If you find Kn on the periodic table of elements, it will tell you how big it is. This chart has all your climbing answers. Kn is like potassium. If you mix potassium and nitrogen you get something interesting. Add water, stir til u like it, boil for 15 minutes on high, add spices and you have a full course meal for the family.
KN can also be found in banannas, bannanas, bannannas. bannannnannnannansnas
(This post was edited by mecalekahi-mekahidyho on Mar 19, 2008, 2:32 AM)
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