Problem 7: Consider again the radar gun and the car described in the preceding problem. Suppose the radar gun sends out only a very short microwave pulse towards the car, in order to measure the car's distance from the gun. For the car's distance stated in the preceding problem, how long will it take for the pulse reflected off the car to be detected by the radar gun? (A) 801 µs (B) 400 µs (C) 801 ns (D) 1601 ns (E) 400 ns Problem 6: A stationary radar gun, positioned right next to a straight road, is aimed at a car, traveling down the road at a speed of 85mph, when the car is at a distance of about 120m from the gun. The radar gun detects a downward frequency shift, fr - fe = -1166HZ, between the frequency, fe, of the microwave emitted by the gun and the frequency, fr, of the microwave reflected off the moving car. Recall that 1mi = 1609m. What is the operating frequency, fe, of the radar gun and in which direction is the car moving, relative to the radar gun? (A) fe (B) fe (C) fe = 9.2 GHz. (D) fe = 9.2 GHz. (E) fe = 2.3 GHz. Car is moving away from radar gun. Car is moving towards radar gun. Car is moving away from radar gun. Car is moving away from radar gun. Car is moving towards radar gun. 4.6 GHz. = 4.6 GHz.

Problem 7: Consider again the radar gun and the car described in the preceding problem. Suppose the radar gun sends out only a very short microwave pulse towards the car, in order to measure the car's distance from the gun. For the car's distance stated in the preceding problem, how long will it take for the pulse reflected off the car to be detected by the radar gun? (A) 801 µs (B) 400 µs (C) 801 ns (D) 1601 ns (E) 400 ns Problem 6: A stationary radar gun, positioned right next to a straight road, is aimed at a car, traveling down the road at a speed of 85mph, when the car is at a distance of about 120m from the gun. The radar gun detects a downward frequency shift, fr - fe = -1166HZ, between the frequency, fe, of the microwave emitted by the gun and the frequency, fr, of the microwave reflected off the moving car. Recall that 1mi = 1609m. What is the operating frequency, fe, of the radar gun and in which direction is the car moving, relative to the radar gun? (A) fe (B) fe (C) fe = 9.2 GHz. (D) fe = 9.2 GHz. (E) fe = 2.3 GHz. Car is moving away from radar gun. Car is moving towards radar gun. Car is moving away from radar gun. Car is moving away from radar gun. Car is moving towards radar gun. 4.6 GHz. = 4.6 GHz.