Halliday, Resnick & Walker — Motion in Two and Three Dimensions: Problem 68

68 A cat rides a merry-go-round turning with uniform circular motion. At time $t_1 = 2.00\text{ s}$, the cat’s velocity is $\vec{v}_1 = (3.00\text{ m/s})\hat{i} + (4.00\text{ m/s})\hat{j}$, measured on a horizontal $xy$ coordinate system. At $t_2 = 5.00\text{ s}$, the cat’s velocity is $\vec{v}_2 = (-3.00\text{ m/s})\hat{i} + (-4.00\text{ m/s})\hat{j}$. What are (a) the magnitude of the cat’s centripetal acceleration and (b) the cat’s average acceleration during the time interval $t_2 - t_1$, which is less than one period?