Spine-Crane Model

[Guest guest]

On spinalfitness.com we are posting illustrations that demonstrate

the structural comparison of the spine in sit-up and heavy lift

crane.

Casler writes (28543) that local global systems must function in

coordinated harmony to provide maximum efficiency and protect one

from injury, he feels, has been missed by some worlds experts and

that enormous complexity is mind-boggling as to how structures

create, absorb and transmit forces. I agree with him on this.

[Note that he was also disagreeing with your belief that you can simplistically

apply a crane model to analyse the functioning of the spine. Are you now

saying that you do not believe that emphatically in a crane model of

the spine? Mel Siff]

Mathematics and the understanding of this complexity is mind boggling

if one must " invent " physics that are confusing or proprietary.

With this " inventing " concept in mind and the understanding (my

understanding anyway) as Einstein pointed out in his theory of

relativity " truth of physics is only as good as it's point of

reference " -- let us examine the wheelbarrow as a second class lever.

The wheelbarrow is second class lever because classical structural

identification determines that the wheel acts as the fulcrum, the

resistance or load is in the bucket of the wheelbarrow and then on

the handles the force of effort is applied to lift the resistance

(the load in the bucket) about the fulcrum or wheel.

This is the classic F (fulcrum) R (resistance) E (effort) structural

identification of second class lever.

[but in your previous letter you stated that there is no such thing

as a second class lever and that a wheelbarrow is not such a lever

system! Did I misread what you wrote? Mel Siff]

Next this second class lever provides greater mechanical advantage in

that the effort (site on handles where you place your hands) has

longer effective effort arm than the resistance's effective

resistance arm. Therefore we can expect a second class lever given

for instance the resistance force is 10 lbs it will be a mechanical

truism that force of effort to lift the resistance about the fulcrum

will be less then the 10 lbs that is the force of resistance.

Is there anyone that does not agree at this point. Is this an

example of logical reality or a proposition of an empirical world?

See reference to this in message 28514

[Mel Siff: How does this disprove that there are second class levers? What

you have argued is totally irrelevant to this issue. We are also still

waiting to receive that oft-requested proof from you that all scientists

and engineers are teaching levers incorrectly. You have avoided

answering that question for so long that I will not post another letter

of yours unless it addresses this issue, plus sorts out the implications

that you know more about levers than any of us in science and

engineering who have gone up to PhD level in fields which cover

levers very thoroughly. You have also not explained why you

have tried to explain levers by introducing topics from the

" strength of materials " which have nothing to do with levers

in statics. Kindly do this, so that this topic stops going around in

endless circles filled with claims, confused language and no proof.

This list does not encourage arguments which continue to

avoid answering questions, providing references and leading to

some sort of useful conclusion. Therefore, I will not publish

anything more on levers unless it offers new or useful information

on that topic and is accompanied by genuine scientific

references. We cannot continue trying to correct your

misconceptions about levers, statics and mechanics if you are

going to proclaim without a shred of genuine evidence that your

views are correct and everyone else's are " wrong " . Give us

the proof and the science or move on to another topic. By the way,

you still have not posted your claims on the Biomch-L list that

scientists and engineers have been teaching levers incorrectly -

when are you going to do so? Maybe the members there will be

able to guide you more than we have. ]

Scherger

Ridgefield Wa