- #1

Leo Liu

- 353

- 149

My textbook says ##\vec r (\theta) = r \hat r (\theta)##, where ##\hat r (\theta)## is the terminal arm (a position vector in some sense). It can be seen that both ##\vec r (\theta)## and ##\hat r (\theta) ## are function of ##\theta##; whereas, the length of the vector ##r## is not. I understand that the unit vector r is a function of the angle because the direction of the arm is changing. However, I would like to know why the authors did not mention whether ##r## is a function of ##\theta##. Thank you in advance :).

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