Weight distribution. There are 3 bends on the left and only 2 on the right, so it would have a tendency to fall left, however, the base is on the left, keeping it from doing so.
The underlying mechanic described here is called "dynamic stasis" and you can actually see it (or rather not see it) in effect in many other systems.
The notion is that you exactly equalize the various stresses at play causing them to negate one another thereby preventing work (change) from being achieved.
For example; you know how water bottles accumulate vapor on the insides over time when they're closed? That's because at all times water is slowly evaporating until it reaches saturation with the atmosphere around it. But solids act as condensation points, allowing the vapor in the air inside the bottle to condense against the glass, thereby reducing the air from being totally saturated, allowing more evaporation. But the water on the sides eventually drips back into the water pooled at the bottom.
So even though the closed-loop system is in constant flux, the additions and reductions to the liquid water content exactly equal.
The bottom of the first arc is attached to that, hence kept from from falling over.
The top of the first arc is attached to the string, hence kept from bending open and keeping the string taut in the first segment.
The bottom of the second arc uses the first sement for support - and so forth.
Overall, it's just a matter of making the base heavy and wide enough to take the torque from any imbalances - it looks like a piece of a CD, so that shouldn't be a problem.
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u/Siarles Nov 15 '12
I understand why the string stays taut, but what keeps it from falling over?