hello,i need help with these 2 questions thank you

Question 1 A 0.300 m long string that has a ball attached to it is spinning around on a flat horizontal plane. It spins over a 90.0 angle in 0.530 s. What is the centripetal acceleration of the ball if it is in uniform circular motion? 8.65x103 m/s2 11.2 m/s2 2.64 m/s2 O 29.3 m/s2 Question 2 A ceiling fan is spinning at 402 rpm just before you turn it off. It comes to rest smoothly over 20.1 s. How many revolutions does it make as it stops? 67.3 revolutions 10.7 revolutions 846 revolutions 423 revolutions