Let's take a wire or a rope. I usually do this with a chain or my scarf.

I fixate one end in my hand and apply rotation (by subtle movements of this endpoint like spinning a lasso). The rope gets into rotation and obtains certain bent shape:


Some part is missing because cellphone cameras ain't great for high-speed photos but I hope you can imagine all the scarf.

The question is: how can I calculate/predict this shape?

Although this problem doesn't seem that bizarre, I have never seen any solution. Nor I have found this question asked anywhere on internet... Must be because I just don't know how to formulate it without pictures.

Also by taking longer rope I get more than one bend:


I apoligize for the quality again. It is even harder to rotate this while taking picture. The form is not spiral, it is more like a shape in a plane that's rotating.

I'll be thankful for explanations, solutions, links or at least a correct formulation of this problem.


Question: Saying Baruch Shepatrani for a girl
Answer: Rav Ovadya Yosef, in Yabia Omer 6 OC 29, writes that one should say the blessing (ברוך שפטרני מעונשה של זו) at the Bat Mitzva celebration without God's name, just as one should recite it without God's name at a boy's Bar Mitzva celebration.