Question

Michael Phelps needs to swim at an average speed of 2.00 m/s in order to set a new world record in the 200 m freestyle. If he swims the first 100 meters at an average speed of 1.80 m/s how fast must he swim the second 100 meters in order to break the record?

Answer 1

Step-by-step explanation:

Given

average speed of Phelps
`v_(avg)=2\ m/s`

total distance
`d=200\ m`

he swims first 100 m at an average speed if
`1.8 m/s`

so time taken is
`t_1=(100)/(1.8)=55.55\ s`

suppose
`t_2` is the time taken to swim remaining half

average velocity is
`v_(avg)=(displacement)/(total\ time)`

`v_(avg)=(100+100)/(55.55+t_2)`

`t_2+55.55=(200)/(2)=100`

`t_2=44.45\ s`

so velocity in the second half is

`v_2=(100)/(45.45)`

`v_2=2.19\approx 2.2\ m/s`