A CD is spinning counterclockwise with a radial velocity of $\omega=30\text{rad}/\sec$. The preface of what I did manage to solve and further details: I was asked what is the period time (12 seconds), the frequency $({1\over 12})$. Then I was said there is a point on the CD that is $15\text{cm}$ away from the center and asked what it the linear velocity. I answered: $v={\pi\over 6}\cdot 15$. Radial acceleration: $a=-v\omega=-{\pi\over 6}\cdot 15\cdot 30\text{rad}$. Linear acceleration: $a=-15\cdot ({\pi\over 6})^2$.
The question I don't get is: As $t=0$, the point is pointing northward. When will it point north again? I am really clueless about that. If I am asked when it will be where it is again then the answer is 12 seconds, but if it refers to wind directions as quarters, then I am baffled. I would really appreciate your help.