(a) 1200 rad/s
The angular acceleration of the rotor is given by:

where we have
is the angular acceleration (negative since the rotor is slowing down)
is the final angular speed
is the initial angular speed
t = 10.0 s is the time interval
Solving for
, we find the final angular speed after 10.0 s:

(b) 25 s
We can calculate the time needed for the rotor to come to rest, by using again the same formula:

If we re-arrange it for t, we get:

where here we have
is the initial angular speed
is the final angular speed
is the angular acceleration
Solving the equation,

Explanation:
see the above attachment to solve the question and get the answer.
hope this helps you.
Answer:
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Haha Rick rolled you
Explanation:
jk my favourite song is Thunder, Despacito