A graph of v(t) is shown for a world-class track sprinter in a 100-m race. (See figure below). Runner Velocity vs. Time 14 12 10 Velocity (m/s) 4 8 10 12 Time (s) (a) What is his average velocity for the first 4 s? m/s (b) What is his instantaneous velocity at t = 4 s? m/s (c) What is his average acceleration between 0 and 4 s? m/s2 (d) What is his time for the race