Q. An athlete completes one round of a circular track of radius $R\ $in $40\ sec$. What will be his displacement at the end of 2 min. $20\ sec$
A) Zero
B) $2R$
C) $2\pi R$
D) $7\pi R$
Explanation
(b) Total time of motion is $2\min{20\ sec = 140\ sec}$
As time period of circular motion is $40\ sec$ so in $140\ sec$. Athlete will complete 3.5 revolution $i.e.,$ He will be at diametrically opposite point $i.e.,$Displacement $= 2R$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.