# What would be the steps to analyze the lateral forces along this looping human chain?

Hi, it’s me of “Physics Setup” fame, so don’t jump down my throat, please, like some of you did before, about exactly what I’m asking, it’s just that here’s a nice clip, and its mechanics intrigued me and I thought it might be used quite well by smart people on SD who are feeling didactic to illustrate which math goes where to analyze torquing and damping. In 3D. With people on skis. But pretend NASA needed to know, because they rely on me.

With kind thoughts, as always,

Leo

The momentum the chain is carrying (gained from skiing downhill) is lower than the physical bonds they’re making with their arms; albeit some human skill and coordination goes a long way to stabilize this, but basically the entire human chain is utilizing gravity to work up a velocity in tandem as a whole. The point-man skier (in white) begins the 360º flip, and this action seems to work down the chain of skiers to flip as well.

Or were you looking for actual math applied to the stunt?

Well, yes, I like seeing math stepped out, and with such discrete points of reference I think it would be a treat.

What struck me in particular was the linkage of the chain–how its stiffness is expressed through variably damping coupled arms (ignoring wrists for the moment) as each unit (person) expended its energy “independently” as a spinning mass influenced–limited, broadly speaking–by the neighbors’ spinning units, each with different dynamics to begin with and each limiting by the linkages, which are changing constantly as the skier’s hold on to each other. So the total trajectory of the gang as a chain, how would it be described from the take-off to the landing?

Maybe my NASA guy gives me take-off weights and angles, and arm strengths and arm kinematics, and wants to know the crooked shape of the flung horizontal beaded chain, so to speak. Yeah…that’s what he wants.

…Honestly, I now think I had an image a ballistics weapons designer who had to analyze the tumble of a thrown net-like weapon (is that called a bolo?) like this…