Two automobiles drive in the same direction along the highway. Each moves initially at speed v = 30 meters per second, (that's 67.11 miles per hour), and the distance between them is D meters.
At time t = 0 seconds, the driver of the car in front, car B, sees a deer in the road ahead and slams on his brakes; as a result, car B decelerates at a = 7.2 meters per second squared. The driver of car A immediately hits his own brakes, which decelerate car A at a = 4.5 meters per second squared.
What is the minimum value of D which allows the driver of car A to stop his vehicle before it crashes into the other car?