If object is not accelerating, the sum of all forces on the object will be equal to ZERO...
Answer:
a) 
b) 
Explanation:
Given:
- initial rotational speed of phonograph,

- final rotational speed of phonograph,

- time taken for the acceleration,

a)
Now angular acceleration:



b)
Using eq. of motion:



Answer:
idk b idk ssry dude good luck tho