Answer:
Speed is a scalar quantity which doesn’t depend on direction of motion.
=> Average speed = Distance/ Time = 270/30 = 9m/s
Velocity is a vector quantity having magnitude and direction. Since the runner runs 270m and returns to the same spot, net displacement is ZERO.
Average Velocity = Displacement/Time
= 0/30 = 0
Hope the difference is clear.
:-)
