Question

a car runs at a constant speed on a circular track of radius 200m taking 62.8s on each lap find the average speed and average velocity at each lap

Answer 1

average speed means total distance covered by particle per interval of time .
e.g
average speed =total distance/total time
= 2π(200)/62.8
=2 × 314 /62.8 =10 m/s

average velocity = total displacement covered per unit time

e.g
average velocity= displacement/time
but we know if any particle moves in circular path and complete the revolution then, displacement is equal to zero.

now,
average velocity =0/ 62.8 =0

Answer 2

Total Distance = 2πr
= 2×(22/7)×200
= 8800/7 m

Displacement = 0 m

Time = 62.8 sec

Average Speed = Total Distance/Total Time
= (8800/7) ÷ 62.8
= 20 m/s (approx)
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Average Velocity = Total Displacement/Total Time
= 0/62.8
= 0 m/s

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