Answer:
3.6 rad/s
Step-by-step explanation:
Given that,
Radius of a compact disc is 6 cm
The angular acceleration of the disc is 1.2 rad/s²
Time, t = 3 seconds
We ned to find the angular velocity of the disc once it is at full speed. The relation between the angular velocity and angular acceleration is given as follows :

So, the angular velocity of the disc is 3.6 rad/s.