you must design a runway that allows planes to reach a ground speed of 65 m/s before they can take off. If the planes accelerate at 2.5m/s/s, what must the minimum length of the runway be?

  d = 845 m

Explanation:

This is an exercise in kinematics, specifically accelerated motion, let's use the equation

         v² = v₀² + 2 a d

since airplanes start from rest their initial velocity is zero

         v² = 2ad

         d = v2 / 2a

let's calculate

         d = 65² / (2 2.5)

         d = 845 m

this is the minimum distance from the track

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min