# Angular acceleration

by elsternj
Tags: acceleration, angular
 P: 42 1. The problem statement, all variables and given/known data A computer disk drive is turned on starting from rest and has constant angular acceleration. If it took 0.640s for the drive to make its second complete revolution, how long did it take to make the first complete revolution? 2. Relevant equations $$\theta$$=$$\theta$$i+$$\omega$$i1/2$$\alpha$$t2 $$\omega$$=+$$\alpha$$t 3. The attempt at a solution Okay I looked this question up on these forums and found it, and what people were saying to do was just not working so see if you can steer me in the right direction. $$\theta$$=$$\theta$$i+$$\omega$$i1/2$$\alpha$$t2 12.56(rads) = 1/2$$\alpha$$(.64)2 solve that for $$\alpha$$ and you get $$\alpha$$ =61.3 (now i know this acceleration is wrong because it's supposed to be 5.26) i would then put the acceleration in a new equation and solve for 6.28 rads but the acceleration isn't even right. why?