Q. An object is moving in a circle of radius 100 m with a constant speed of $31.4\ {ms}^{- 1}$. What is its average speed for one complete revolution?
A) Zero
B) $31.4\ {ms}^{- 1}$
C) $3.14\ {ms}^{- 1}$
D) $\sqrt{2} \times 31.4\ {ms}^{- 1}$
Explanation
(b) The time taken by the particle for one complete revolution.
$t = \frac{2\pi r}{speed}$
$= \frac{2 \times 3.14 \times 100}{31.4} = 20s$
$Hence,\ averge\ speed\ is\ $
$v_{av} = \frac{2 \times 3.14 \times 100}{20} = 31.4{\ ms}^{- 1}$
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Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.