Answer:
Step-by-step explanation:
(a)Disc rotates at constant angular velocity
constant angular velocity denotes zero angular acceleration therefore disc has only radial acceleration and no tangential acceleration
because


(b)If disk angular velocity is increasing uniformly it implies there is presence of constant angular acceleration
therefore Point on disc have both tangential and radial acceleration
(c)For First case
Neither component of linear acceleration is changing as disc rotates with constant angular velocity
For second case only radial component of linear acceleration is changing while tangential acceleration is same.