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!
