Walking a Tightrope

I have many irrational fears like spiders, small spaces and tiny little holes that are too close together. However, heights, which is quite a reasonable fear to have, is not one of them. My liking of heights is only present when I feel safe or secure. When I rock climb and zip line, I have a harness and when I look over the edge of the cliff, my feet are grounded therefore, I feel safe. Walking a tightrope is something I would never consider because the element of security is absent. There are no safety nets, harnesses or any protective equipment. It would just be me and the rope. Nonetheless, walking a tightrope is an impressive skill, one that takes years of practice, a lot of patience and courage and, most importantly, a good understanding of physics.

No doubt, the entirety of walking a tightrope is centered around balance and the moment of inertia. The moment of inertia is an object’s ability to resist a change in motion around an axis, the axis being the rope. This is the reason that tightrope walkers carry a very long pole. The equation for the moment of inertia is I=mr², which is the product of mass and distance from axis squared. The pole places greater distance of mass from the rope resulting in an increase in the moment of inertia. This, in turn, increases the period of oscillation which is the repetitive variation in a measure. This all allows for any wobbles or disruption to the equilibrium to occur slowly, giving the walker time to respond and restore equilibrium.

High wire 2 © Graeme Maclean CC-BY 2.0

The conditions of the rope and position of the walker must also be taken into consideration. The rope cannot be too loose allowing for lots of swinging and movement, but it also must not be too tight, creating more vibrations. The Journal of the Royal Society Interface claims “an optimal sag of about 3 feet where balancing is easiest” is the “sweet spot” of a rope slack. The posture of the walker is considered to be one of the most important elements of a successful walk. The walker must bend their knees in order to lower their center of gravity as this increases stabilization. If a force were to be applied upon a tall and narrow building versus a small and stout one, the first is more likely to topple over. Although it is a simple physics concept, it is difficult to execute 150 meters in the air. However, it is important that walkers do not achieve this lowered center of gravity by leaning forward although, it makes them closer to the rope, it disturbs the equilibrium.

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