An athlete completes one round of a circular track of radius $R$ in 40 sec . His displacement at the

Question

An athlete completes one round of a circular track of radius $R$ in 40 sec . His displacement at the end of 2 min 10 will be\

Professor PC Thomas Classes · Answer

Total time of motion on circular track\ $=2 	imes 60+10=130$ s\ Time period of revolution $=40 \mathrm{~s}$\ Therefore, displacement in time ( $=3 	imes 40=120 \mathrm{~s}$ )\ $=$ zero as athlete will be reaching at the starting point.\ Thus, displacement in 130 seconds\ $=$ displacement in 10 seconds. He will cover a quarter circle.