An athlete completes one round of a circular track of radius R in 40 s What will be his displacement at the end of 2 min 20 sec ?

Question

An athlete completes one round of a circular track of radius R in 40 s What will be his displacement at the end of 2 min 20 sec ? (A) Zero (B) 2 R (C) 2 π R (D) 7 π R

Tardigrade Admin · Accepted Answer

Total time of motion on circular track =2 × 60 +20=140 s Time period of revolution =40 s. Therefore displacement in time (=3 × 40=120 s )= zero as athelete will be reaching at the starting point. Thus displacement in 140 seconds = displacement in 20 seconds =2 R

Q. An athlete completes one round of a circular track of radius R in 40 s What will be his displacement at the end of 2 min 20 sec ?

Zero

$2 R$

$2 π R$

$7 π R$

Total time of motion on circular track $= 2 \times 60$ $+ 20 = 140 s$
Time period of revolution $= 40 s$ .
Therefore displacement in time $(= 3 \times 40 = 120 s) =$ zero as athelete will be reaching at the starting point. Thus displacement in 140 seconds $=$ displacement in 20 seconds $= 2 R$