An athlete runs once around a circular track of perimeter 400 m and returns to the start in 50 seconds. Her average SPEED and average VELOCITY are:
ASpeed 8 m/s, velocity 8 m/s
BSpeed 0, velocity 8 m/s
CBoth 0
DSpeed 8 m/s, velocity 0
Answer & Solution
Correct answer: D. Speed 8 m/s, velocity 0
Average SPEED = total distance / time = 400 / 50 = 8 m/s. But the start and finish are the same point — so DISPLACEMENT = 0, and average velocity = displacement / time = 0. This is the classic distinction: for a closed path, speed > 0 but velocity = 0.
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