In the attachment is my problem.
I don't think the bar will be in circular motion. The motion is rather complex since the string 1 is involved. And what is theta anyway? You haven't defined it yet.
First of all, this question is not homework, Unknowingly was moved to this section!
Thanks for reply
Suppose string 1 is a solid and fixed bar; not a string actually :D, and on which the blue bar can freely rotate.
As for theta, as I said, it's how many degrees the blue bar rotates after string 1 is cut, in other words, it's the angle between the negative x axis and the blue bar.
Use the law of energy conservation to find the relationship between angle theta and angular velocity, and then compute the integral to find angle theta w.r.t. time t. The integral is hard to compute, so use wolframalpha (http://integrals.wolfram.com/index.jsp) or any other tool. I believe the result won't look nice at all.
hey this is a typical textbook problem.
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