 #1
Kakainsu
 32
 5
 Homework Statement:

Hi guys,
Currently, we are discussing the physics of wave swing with and without the constant changing of the rotating axis. Former situation gives me problems. Our teacher presented a solution (attached), in which he explained the relationship of the actual tilt between the rotating axis and the chains (beta) and the tilt between rotating axis and the vertical axis (alpha). He makes use of the law of sine ("Sinussatz" in German).
I do understand the explanations with one exception: How can we assume, that beta is the same at the lowest and highest point of the ride? To go one step further, does that mean, that beta is constant at a given alpha for all "positions" on the described circle at that moment? I hope you know what I mean, it's hard to express :)...
Edit: I now included another "commented" pic, maybe it now is easier to understand...
 Relevant Equations:
 No equations needed, I guess...
Yeah, as I said, i have no idea why we can assume beta to be the same for any position at given alpha.