I believe that car "B" is passing car "A" because if the two cars are side by side the current speed is unimportant (it is like both cars are sitting still). Thus the rate of acceleration is greater for car "B" and it will be passing car "A" as they emerge from the tunnel.

At time t when they came out of the tunnel they were side by side, so they would be traveling at a constant speed. At this point, all that would matter would be the acceleration. Thus, Car B would be passing car A.

In this problem the car traveling at 40km/h at an acceleration of 60(km/h)/min is the car that would be passing the other as they come out of the tunnel. Because both cars are comming out of the tunnel at the same time, we need not have to worry about the original velocities of the cars. Therefore the car with an acceleration of 60(km/h)min would be the car passing the other.

Car B will pass Car A as they come out of the tunnel. Even though Car B has a slower initial speed, its acceleration is greater, and therefore its speed as it passes Car A will be greater. The speed of Car B is increasing at a greater rate than the speed of Car A. At the instant the cars leave the tunnel, I think Car B will be ahead of Car A.

I'm thinking that B will eventually pass A, because B is increasing its speed (to A's current speed), while A is decreasing its speed (to B's current speed).

Car B will be passing Car A as they pass out of the tunnel. Although, Car A is traveling at a higher speed, this speed will decrease since the acceleration is low. On the other and Car B will make up for the lack of initial speed by having a higher acceleration. matter would be the acceleration. Thus, Car B would be passing car A.