Author Topic: Puzzle (Mayhem!)  (Read 5438 times)

KC

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Puzzle (Mayhem!)
« on: April 15, 2006, 02:34:12 AM »
Old drawing i maid; i think inside the microcosm of knots these same forces can play out.  CG is center of gravity, meaning that this is bottom heavy

"Nature, to be commanded, must be obeyed" -Sir Francis Bacon[/color]
East meets West: again and again, cos:sine is the value pair of yin/yang dimensions
>>of benchmark aspect and it's non(e), defining total sum of the whole.
We now return you to the safety of normal thinking peoples

Willeke

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Re: Puzzle (Mayhem!)
« Reply #1 on: April 15, 2006, 02:43:42 PM »
KC,
Looking at the puzzle I wondered is the mention of 100# the weight to be moved or the force to be used to move the load.
Or is it a part of the question and am I asking for help you should not give?
Or something else again.

Willeke,
(who did not remember as much of the lessons in fysics as she should.)
"Never underestimate what a simple person can do with clever tools,
nor what a clever person can do with simple tools." - Ian Fieggen

Writer of A booklet on lanyards, available from IGKT supplies.

KC

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Re: Puzzle (Mayhem!)
« Reply #2 on: April 15, 2006, 03:36:10 PM »
Well, i never had any of that fysics stuff; this is just pure paying the BeaST (Blood, Sweat and Tears) at work, and observations to maximize.  

This is intended to be a free hanging weight of 100# total supported by the line hitched to the overhead anchor/support.  No lifting, just how much tension is on the sling holding both of the bottom pulleys. ???
« Last Edit: April 15, 2006, 04:34:39 PM by KC »
"Nature, to be commanded, must be obeyed" -Sir Francis Bacon[/color]
East meets West: again and again, cos:sine is the value pair of yin/yang dimensions
>>of benchmark aspect and it's non(e), defining total sum of the whole.
We now return you to the safety of normal thinking peoples

DerekSmith

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Re: Puzzle (Mayhem!)
« Reply #3 on: April 17, 2006, 02:43:54 AM »
Please excuse me KC but I do not fully understand you diagram.

May I assume that the top pulley is spindled onto the orange panel.

May I also assume that the orange panel with the brown part  marked Low CG is the object being suspended with a mass of 100#.

This leaves the question of where the sling holding the two lower pulleys is tethered.  It seems from the diagram that the sling is fixed to the orange panel by the black ring at its base.

You have marked the link between the fixing ring and the two pulleys as the part you wish to determine the loading in.

If this understanding of your drawing is correct then as both sets of pulleys are fixed to the same panel and they are not allowed to move relative to oneanother then there is no pulley efficiency or pulley effect to be had.  The assembly is nothing more than a rather complicated knot fixing the support line to the bottom pulley.

If this is the case then the whole of the object mass (100#) is transfered through the sling to the support line, thereby giving all parts the same loading of 100#.

However, I cannot believe that this is your meaning of the assembly, otherwise why would you have drawn such a complicated assembly with pulleys and asked a question where some degree of pulley effect is expected, so if I have made incorrect assumptions please advise me which parts differ from my assumptions.

Derek Smith

KC

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Re: Puzzle (Mayhem!)
« Reply #4 on: April 17, 2006, 02:57:31 PM »
Hey Derek,

 The whole board jig weighs 100#, the top pulley is connected to the board; the bottom 2 pulleys are connected together, then anchored to the board.

The puzzle is how much tension on the lower strap, that connects both lower pulleys to the board.  Ya got all that right.

But, 100# is not the correct answer  :-[ as tested by scales.  This is part of my knot theory; showing a magnified view of the interior workings; of how knots work.

i guess i'll let this stand for a few more daze, before answering/ going on to puzzle 2 of the same rig.  i think rope rigging with pulleys etc. work with the same materials and forces as knots themselves.

i originally made this to illustrate the flow of force; and how i rig stuff in tree work.
« Last Edit: April 17, 2006, 02:57:56 PM by KC »
"Nature, to be commanded, must be obeyed" -Sir Francis Bacon[/color]
East meets West: again and again, cos:sine is the value pair of yin/yang dimensions
>>of benchmark aspect and it's non(e), defining total sum of the whole.
We now return you to the safety of normal thinking peoples

DerekSmith

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Re: Puzzle (Mayhem!)
« Reply #5 on: April 17, 2006, 05:04:12 PM »
Wow KC, now you really got my attention.

Before you give the game away, may I ask some more questions please.

You say the force in the sling was measured by scales.  Would you please show exactly how you measured that force and how you connected the scales.

Derek

DerekSmith

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Re: Puzzle (Mayhem!)
« Reply #6 on: April 17, 2006, 06:19:59 PM »
OK - Strike that.

Mentally turning the board around and fixing it to the deck (forgetting that it weighs 100#) and thinking of 100#pull being delivered through the supporting Line.

The pulley system has a mechanical advantage of 4:1 so the pulley force would be answer G - 400#.

The support line would only be applying 100# so the orange board would be having to resist 100# force to move it.  This equates to the 100# weight you ascribed to the pulley assembly in the question.

This would also mean that 300# of the 400# force was being opposed by the pulley and fixing point the other end of the board - combined force of 600# trying to crush the ends of the board together.  Is this what you are getting at about the forces acting out within a knot?

Derek

KC

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Re: Puzzle (Mayhem!)
« Reply #7 on: April 17, 2006, 06:43:48 PM »
Yes, ya figured it out lots faster than i did originally, or anyone else i've shown it to!  i even was told by an engineer that the force was not created, but rather that the spring in the scale was rpoviding this force (whatever the heck that means); after a page of physics formulaes with all kinds of strange charachters, that quite frankly looked like greek to my uneducated person.

And ya beat me to the punch; cuz the next question woulda been, okay; so now we say 400# pushing up on 100#, yet the weight is not lifted?

The answer there is that the top pulley + line termination on the board together are 300# pushing down as 400# pushes up; thus no movement, for the remainder of 100# just supports the 100# weight.

But, internally inside we now have arguably 300# (300# down, against 400# up)of compressing force created,  this could serve to crush board, or perhaps even firm it!  Inside a knot lacing, this would be force generated for more positive lock on host load or line from the 100# load pull.  Argueably 700# (less 100# by pull down of weight) of crush, but, the 300# down, needs 300# up to exist; so i think would just measure that....

Reversing the view as the line is pulling rather than load is key; and is corect as promised by the equal and opposite reaction giving us 2 avenues to view the same effect.



i set this up with fish scales in center of strap holding bottom pulleys.  Using a broom stick  with chainsaw on the bottom.  This gave bottom heavy example.  You don't need pulleys, can use slippery quick links etc. and slippery string at such light weight.  Scales aren't needed, as the differance, as the extra tension in strap can be felt,a nd even heard when strummed.  i set it up like this in yard to leave for awhile a few years back, and show low budget way to prove.  i also set it up with 3 possible support lines laced: A) single pull support, B) jsut one lower 'pulley' C) 2 lower 'pulleys'/ quick links.  This way without changing anything else you can let it hang by (A) then pull it higher by (B), then release that (lays back into (A) support) and pulling by (C).  Like i said you can undeniabley feel and hear the tension differance on the connecting line/sling in question.  Some thogut it was some kind of trick; as it hung there for months!

Word of caution, top broomstick is much more lively, when changing from (C) to (A) and can dent your coconut by the amplitude/impact of the sudden change in forces!

Very good!

« Last Edit: April 17, 2006, 06:50:39 PM by KC »
"Nature, to be commanded, must be obeyed" -Sir Francis Bacon[/color]
East meets West: again and again, cos:sine is the value pair of yin/yang dimensions
>>of benchmark aspect and it's non(e), defining total sum of the whole.
We now return you to the safety of normal thinking peoples

KC

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« Last Edit: April 29, 2006, 02:08:51 PM by KC »
"Nature, to be commanded, must be obeyed" -Sir Francis Bacon[/color]
East meets West: again and again, cos:sine is the value pair of yin/yang dimensions
>>of benchmark aspect and it's non(e), defining total sum of the whole.
We now return you to the safety of normal thinking peoples