Question

an athletes one round of a circular track of diameter 200m in 40s.what will be the distance covered and the displacement at the end of 2 minutes 20s?

Answer 1

the circumference=200*22/7
=4400/7
speed of the man=distance/time=4400/(7*40)=110/7m/s
2min 20 sec=140 sec
the total distance travelled= speed *total time=140*110/7=2200m
no. of rounds taken= 2200/(4400/7)=3.5
the total displacement= 2200/7m

Answer 2

Diameter= 200 m Circumference= πd = π200 Time taken to complete one revolution =40s Final time = 2 minutes 20s = 140s Therefore, no.of revolutions in 140s = Total time taken ÷ Time taken to complete one revolution=140÷40=7÷2=3.5 rounds Distance covered = no.of revolutions * circumference =3.5 *π200 = 2200m As the no. of revolution is 3.5 so it clearly shows that the athlete after completing 3 rounds completed another half round. Therefore, displacement = 200m