A highway police radar operating at 10 GHz observes a Doppler shift of 1,500 Hz when the radar is pointed at a moving car. What is the radial speed of the car toward the radar in miles per hour?
A radar emits waves. The waves reflect from a barrier (the car). Since the car moves, the incident waves reflect with some additional shift, which causes Doppler shift.
45 m/s is 162 km/h.