The process that produces the energy radiated by stars is nuclear fusion in the core.
For a star on the main sequence, it's the fusion of hydrogen nuclei into helium.
Answer:
The magnitude of the average angular acceleration of the disk is
.
Explanation:
Given that,
Angular velocity, 
The disk comes to rest, 
Time, t = 0.234 s
We need to find the magnitude of the average angular acceleration of the disk. It is given by change in angular velocity per unit time. So,

So, the magnitude of the average angular acceleration of the disk is
.