A spy sits atop an overpass 30 ft above a rural road. Her target, driving a sleek sports car, passes under the overpass and travels away from the spy along the road. She tracks the car with a specialized device that tells her how quickly the angle between the horizontal and her line of sight to the car is changing. A one moment, the car passes a point on the road 40 ft beyond the point directly below her position. She notes that, at that precise moment, the angle between the horizontal and her line of sight is decreasing at a rate of 1/2 rad/sec.

How fast is the car traveling at that point in time?