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

Answer:

It takes 6.52 s to complete the 150 m track.

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:

$t=\frac{x_{2}}{V_{f}}$

$t=\frac{111.5}{17.1}$

$t=6.52\: s$

I hope it helps you!