Question

Olympic swimmer Michael Phelps swam at an average speed of 2.01m/s during the first half of the time needed to complete a race. What is his average swimming speed during the second half of the race if he tied the record which was at an average speed of 2.05m/s?

Answer 1

Here average speed for given motion is defined as ratio of total distance covered by total time

so here we can say

`v = (d)/(t)`

here total distance can be calculated by formula

distance = speed * time

`v = (v_1*t_1 + v_2*t_2)/(t_1 + t_2)`

here given that its average speed is v = 2.05 m/s

for first half let the time is "t " seconds and the speed for that is 2.01 m/s

and for next half time will be same and it is "t " seconds again

so by plug in all data in above equation we have

`2.05 = (2.01* t + v* t)/(t + t)`

`2.05 * 2 = 2.01 + v`

`v = 2.09 m/s`

so its speed for next half must be 2.09 m/s