Compute your average velocity in the following two cases: (a) You walk 73.6 m at a speed of 1.79 m/s and then run 73.6 m at a speed of 4.31 m/s along a straight track. (b) You walk for 1.00 min at a speed of 1.79 m/s and then run for 1.30 min at 4.31 m/s along a straight track.