Guess this goes here?

[singunner]

I've looked over the web a bit but can't find any proper information on this. I'm aware of the principle that if you have a 10m rope that barely breaks with 100kg hanging from it, the same rope at 5m will not break from the same 100kg. I've been under the impression that this is called "tensile strength", but I could be misremembering.

What I'm looking for is some sort of formula that determines the decrease in the strength of a rope as it grows in length. Any help would be appreciated.

[kenwoodallpromos]

I heard velocity increases force, may have an effect.

[46zilzal]

I heard velocity increases force, may have an effect.
basic physics FORCE=mass x acceleration

[linrom1]

I've looked over the web a bit but can't find any proper information on this. I'm aware of the principle that if you have a 10m rope that barely breaks with 100kg hanging from it, the same rope at 5m will not break from the same 100kg. I've been under the impression that this is called "tensile strength", but I could be misremembering.

What I'm looking for is some sort of formula that determines the decrease in the strength of a rope as it grows in length. Any help would be appreciated.

I have an answer for you, but you might NOT like it.

Link (http:///www.newton.dep.anl.gov/askasci/eng99/eng99447.htm)

Question - A few friends and I were talking about cable length
and strength. Our question is: Does the length of chain, cable or
rope degrade the overall strength? Longer=stronger? or
shorter=stronger? and most importantly, WHY?
---------------------------------------
This is an engineering question.

Generally, a chain, cable, rope, or any long object under stress, will get
less strong with increasing length. Not always, but usually.

For any long object under stress, there is always a "weakest link" which
fails first. Once the bad link of a chain, or one bad section of rope
fails, then the whole thing comes apart.

The longer an object is, the greater the chance of getting a "weak" or "bad"
link present. If the factory always made chain links or rope absolutely
perfectly, then there would never be any weak links, and length would not
matter.

This principle can be applied to other areas as well. For example, a
machine with a lot of parts is expected to be less reliable than one with
few parts, because chances are that one of those many parts will have a
problem.

Bob Erck
================================================== =================
Hi Duane
Cable strength is determined by properties of the material out of
which the cable is made and the cross-sectional area. Cables come in
different configurations of bundles and stranding, but that is done
primarily for flexibility. The overall length of a cable really has
no bearing on the strength, however, it will affect how much the
cable will stretch under a load. If you consider defects that may
contribute to premature failure, statistically the longer the cable
is, the more likely there will be something that may contribute to
failure.
Hope this helps.

Bob Froehlich
================================================== =================
As whatever tension you place upon a rope or chain is shared equally down
its length, its strength should remain the same whether it is very short or
very long.

In practice, it is worth noting that rope and chain both have characteristics
of their own. If you suspend something from a great length of chain, the
weight of all that extra chain must be added in, reducing your useful load.
Also, the longer a piece of rope or chain is, the greater the chance of some
imperfection reducing its strength.

Ryan Belscamper

[kenwoodallpromos]

Maybe the best way to keep the 100kg "hanging" is to "hang" the weight from a bungee cord the does not touch the ground! Just make sure the 100kg is facing Mecca!!LOL!!

[singunner]

Linrom,

Thank you very much for that. That's exactly what I was looking for. I had assumed it was a mathematical/physics reason rather than a quality control reason. That's very interesting.

And could we get a moderator to delete or close this thread? It was vaguely handicapping-related but doesn't matter at all given the answer, and I think there are plenty of other open threads in this seciton of the forum for moronic dialogue.

[Tom]

Now I heard it differently today - that length played a key role in whether the nec breaks or not, or if the head pops off. Believe it or not, I heard it on the Al Franken Show! (I try to see how the other half thinks sometimes).

Found some interesting stuff on that here:

http://en.wikipedia.org/wiki/Hanging

[michiken]

The fatter you are the shorter the rope! (http://en.wikipedia.org/wiki/Official_Table_of_Drops)

[singunner]

I guess I misread "Off Topic - General" as meaning "a location for topics not related to any of the other listed categories", when in fact it's a warning that people will pollute a thread with single-minded, unrelated crap.

Tom, weren't you just laying in to Sec about posting unrelated crap in the MLK thread?