The researchers created a simple model of a person on a rope with forces, masses, angles, and velocities to describe how the rope and person respond to each other. They also considered the sensory systems that alert us when our bodies start to teeter, including our eyes, the organs of our inner ear, and orientation information from our ankles and knees. In their calculations, they suggest that rapid information about falling provided by the inner ear is sufficient to help a rope walker maintain his or her balance.
The team also discovered that a key feature affecting balance is the rope's sag. A tight rope with little sag makes quicker vibrations, whereas a loose rope with a lot of sag makes larger back-and-forth swings. Between these two challenging extremes exists a "sweet spot"—an optimal sag of about 3 feet where balancing is easiest, the researchers report online today in the Journal of the Royal Society Interface.
The sag of a rope changes as a person walks along it, and it is greatest when the person is halfway across. A rope walker who finds the sweet spot can balance more easily because there, "all your sensory control information can be easily tuned to the dynamics of the rope," says study author Paolo Paoletti, an applied mathematician.. "The time that you need to react coincides with the time that the rope makes one swing."
Knowing how it's done doesn't make me want to try it. Read more on this study at ScienceNOW. Link -via the Presurfer
(Image credit: Steffen A. Frost)