Question

A car driver stops at a traffic light when the light shows RED. A truck driver arrives at the traffic light just when it shows GREEN. He continues driving at a constant speed of 32 kmh-1. Suppose the road beyond the traffic light is straight and flat, how long will the car driver take to catch up with the truck, if he is driving at a constant acceleration of 2 ms^-2 in the direction of the truck ? Assume the average reaction time for a driver is 0.7 s

Answer 1

Explanation:

let after t second the car driver take to catch.

speed of truck (Vt) = 32×5/18 = 80/9 m/s

=> distance covered by truck in time t

= distance covered by car in time t

=> Vt ×t = (1/2) at²

=> Vt = (1/2) at

=> 80/9 = (1/2)×2×t

=> t = 80/9 = 8.8888 S

since average reaction time = 0.7S

=> t = 8.8+0.7 = 9.5 S

hope this helps you