Answer to Question #127757 in Physics for Randal Rodriguez

Question

At the instant the traffic light turns green, a car that has been waiting at an intersection starts ahead with a constant acceleration of 3.2m/s2. At the same instant a truck, traveling with a constant speed of 20m/s overtakes and passes the car. How far beyond its starting point does the car overtake the truck in meters?

Answer 1

$S_1=S_2$

$vt=at^2/2\to t=2v/a=2\cdot20/3.2=12.5(s)$

$S=at^2/2=3.2\cdot12.5^2/2=250(m)$. Answer