A cat rides a merry-go-round turning with uniform circular motion. At time t1 = 2.20 s, the cat's velocity is (3.90 m/s) + (3.70 m/s) , measured on a horizontal xy coordinate system. At t2 = 5.30 s, its velocity is (-3.90 m/s) + (-3.70) . What are (a) the magnitude of the cat's centripetal acceleration and (b) the magnitude of the cat's average acceleration during the time interval t2 - t1, which is less than a period of the motion?