A cat rides a merry-go-round turning with uniform circular motion. At time t1 = 1.80 s, the cat's velocity is (3.60 m/s)i + (2.00 m/s)j , measured on a horizontal xy coordinate system. At t2 = 5.70 s, its velocity is (-3.60 m/s)i + (-2.00)j . 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 t_(2) – t_(1), which is less than a period of the motion?