Number 5 part a b and number 6

5) sprinter running on a circular track has a velocity of constant magnitude 9.20 m/s and a centripetal acceleration of magnitude 3.80 m/s'. What are (a) the track radius and (b) the period of the circular motion? 6) A centripetal-acceleration addict rides in uniform circular motion with radius r = 3.00 m. At one instant his acceleration is a = (6.00 m/s' )i+(-4.00 m/s? )j. At that instant, what are the values of (a) v -a and (b) rxa