Question

a distance runner jogs 5 km around a small lake. she travels the first half of the distance at a constant speed of 4 m/s. she travels the second half of the distance at a constant speed of 2 m/s. what was the average speed of a jogger for the entire trip?

Answer 1

First half distance is covered by speed 4 m/s

so the time taken by the jogger to complete the distance

`t = (2500)/(4)`

`t = 625 s`

next half distance is covered by speed 2 m/s

so the time taken by it to cover the distance

`t = (2500)/(2)`

`t = 1250 s`

now the total time of the journey

`T = 1250 + 625 = 1875 s`

now the average speed is given by

`v = (D)/(T)`

`v = (5000)/(1875)`

`v = 2.67 m/s`

so its average speed will be 2.67 m/s