Answer:
B. Radio waves are reflected off of the moving object, which causes a change in frequency that can be analyzed by the software of the radar gun to calculate the object's speed.
Explanation:
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As an object moves away from a radar gun, each successive wave is reflected off of the object onto the radar gun at a position farther than the previous wave. As a result, the distance between two successive crests increases and the frequency of the reflected wave decreases. Similarly, when an object moves toward a radar gun, each successive wave is reflected back to the radar gun at a position closer than the previous wave. As a result, the distance between two successive crests decreases and the frequency of the reflected wave increases. A decrease or increase in frequency is analyzed by a software program in radar guns to determine the speed of the object.
Therefore, radio waves are reflected off of the moving object, which causes a change in frequency that can be analyzed by the software of the radar gun to calculate the object's speed.