Average speed = (total distance) / (total time)
First segment:
15 m/s for 10 sec; distance covered = (15 x 10) = 150 m
Second segment:
20 m/s for 20 sec; distance covered = (20 x 20) = 400 m
Third segment:
30 m/s for 15 sec; distrance covered = (30 x 15) = 450 m
Total time = (10s + 20s + 15s) = 45 sec
Total distance = (150m + 400m + 450m) = 1,000 m (1 km)
Average speed = (1,000 m) / (45 sec) = 22.22 m/s
