Homework Help: Simple angular problem but answer is wrong

When a turntable rotating at 33 1/3 rev/min is shut off, it comes to rest in 26 s. Assume constant angular acceleration.
(a) Find the angular acceleration.
rad/s2

(b) Find the average angular velocity of the turntable.
rad/s

(c) Find the number of revolutions it makes before stopping.
rev

For Part A I did:
omega = omega initial + alpha * t
omega = alpha * t
omega/t = alpha

(33.3 rev/min) / (26s) * (2Pi rad) / (1 rev) * (1 min) /(60s)
= .1341218402 rad/s^2 = approx .13 rad/s^2
but this is wrong.

For Part C:
displacement = omega initial + 1/2 alpha * t^2
= 1/2(.1341218402 rad/s^2)(26s)^2
=45.33318199 approx = 45 revolutions.

For Part B is it taking the average of initial omega velocity and final omega velocity?

 

Hmm, I put -.13 rad/s^2 but it was still wrong and as for part C I calculated to approx 71 revolutions and it was wrong. what else I did wrong?

Initial angular velocity / 2
initial angular velocity is = angular acc. * 1s correct?

 

Oh, I guess I should've put more decimal places rather than just -.13 rad/s^2
and for part B, you are right it was 7.22, I saw it as 72.

Thanks for the clarification!