(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The problem and answers are given in full through the following image:

[URL]http://ekdhl.net/files/mechanics.JPG[/URL]

2. Relevant equations

Equations 2/13 and 2/14 are these:

[itex]\textbf{v} = r'e_{r} + r\theta 'e_{\theta}[/itex]

[itex]\textbf{a} = (r''-r\theta '^{2})e_{r} + (\theta ''r + 2r'\theta ')e_{\theta}[/itex]

3. The attempt at a solution

I could solve the introductory problems that had to do with polar coordinates easily, and I have worked with both spherical and polar coordinates in calculus classes, and haven't had a problem with it. But I can't figure out what the relationship is between [itex]\beta[/itex] and that the other metal bar, that is, how their movements correlate. The only thing I could come up with, and have tried, is to use the cosine theorem and the taking its derivative with regard to time. But this did not work, and dimensional analysis would also confirm that it did not yield the answer that I wanted.

So I'm stumped, and would appreciate your help!

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# Mechanics problems, about the use of polar coordinates

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