Two cars approach each other on a straight and level road. Car A is traveling at 75 km/h, due north and car B is traveling at 45 km/h, due south. Both velocities are measured relative to the ground.
-At a certain instant, the distance between the cars is 15 km. How long will it take, in seconds, from that instant for the two cars to meet?
A)450 s
B)900 s
C)720 s
D)1200 s
E)1900 s

Question

Quizplus · Accepted Answer

The relative speed of the two cars is 75 km/h + 45 km/h = 120 km/h. The time taken to cover the 15 km distance at this speed is 15 km / 120 km/h = 0.125 hours, which is 0.125 * 3600 seconds = 450 seconds.

Two Cars Approach Each Other on a Straight and Level