1. The problem statement, all variables and given/known data Radar guns emit radio waves. The radar gun measures the beat frequency between the returning waves. How does the radar gun determine velocity? A. By measuring beat frequency between two consecutive reflected waves. B. By measuring the beat frequency between a wave reflected from a stationary object and one reflected from a moving object. C. By measuring the beat frequency between a wave reflected from two separate objects moving at the same speed. D. By measuring the beat frequency between a wave reflected from two separate objects moving at different speeds. Answer is B. 2. Relevant equations Fbeat = |F2 - F1| the doppler equation: Fs / v+or-vs = Fl / v+or-vl 3. The attempt at a solution My interpretation. Correct me if i'm wrong, please: A wave is emitted, reflects off object, and goes back to the radar gun. The frequency of the wave changes due to doppler effect. As new waves are emitted, a beat is produced which can measure the difference between the shifted wave and the new wave. But beyond this, i'm not sure. Been staring at this question for an hour and could use some help. Thanks very much.