Question

On a 150 m straight sprint, a cyclist accelerates from rest for 4.5 s at 3.8 m/s2. How long will it take her to complete the 150 m track, assuming she maintains her speed for the remaining part of the track?

Answer 1

It takes 6.52 s to complete the 150 m track.

Step-by-step explanation:

Let's find the position of the cyclist during the acceleration.

`x_(1)=v_(0)t+0.5at^(2)`

`x_(1)=0.5(3.8)(4.5)^(2)`

`x_(1)=38.48\: m`

Now, the final speed at this distance will be:

`v_(f)=v_(0)+at`

`v_(f)=3.8*4.5`

`v_(f)=17.1\: m/s`

Now, we know that x(tot) = 150 m, the remaining part will be:

`x_(2)=150-38.48=111.5\: m`

Therefore, the time is:

`t=(x_(2))/(V_(f))`

`t=(111.5)/(17.1)`

`t=6.52\: s`

I hope it helps you!