Question

A car travelling at a speed of 50 mph. The driver saw a roadblock 80m ahead and stepped on the brake causing the car to decelerate uniformly at 10 m/s². Find the distance from the roadblock to the point where the car stopped. Assume perception reaction time is 2 seconds.

Answer 1

$v=50~\frac{mi}h=22.35~\frac ms,$

$l'=l-vt=35.3~m,$

$s=l'-\frac{v^2}{2a}=10.3~m.$