writing in science 2

question(9.67) -A computer disk drive is turned on starting from rest and has constant angular acceleration. If it took 0.0865 s for the drive to make its second complete revolution, (a) how long did it take to make the first complete revolution, and (b) what is its angular acceleration, in 

answer- a) 0.0612 s

b)3358.98 rad/s^2