Question

The city is trying to figure out how long the traffic light should stay yellow at an intersection. The speed limit on the road is 45.0 km/h and the intersection is 23.0 m wide. A car is traveling at the speed limit in the positive direction and can brake with an acceleration of -5.20 m/s2. (a) If the car is to stop on the white line, before entering the intersection, what is the minimum distance from the line at which the driver must apply the brakes? (3sigfigs)

Answer 1

Vo = 45km/h = 45000m/3600s = 12.5 m/s.

V^2 = Vo^2 + 2a*d.
0 = (12.5)^2 - 2*5.2*d.
d = ?.