physic 難題 8

Distance travelled from:
I to II = 2 m
II to III = 4 m
III to IV = 8 m
Hence, total distance travelled = (2+4+8) m = 14 m
Average speed = 14/18 m/s = 0.778 m/s

Assume I is at the origin with coordinate (0,0).
The x-coordinate of IV is (2+8) m = 10 m
The y-coordinate of IV is 4 m
Hence, the coordinate of IV is (10, 4)
Displacement = square-root[10^2 + 4^2] m = 10.77 m
Average velocity = displacement/time = 10.77/18 m/s = 0.598 m

I would choose option F as the answer.