Radar or radio detection and ranging systems use reflected microwaves to determine a flying object's direction, distance and speed. Radar sends out bursts of electromagnetic waves in a particular direction, any object within radar's range will be detected and its direction will be known. These waves are reflected back off the flying object and the time duration needed for the motion of waves is used to calculate the distance of the object. Since the waves travel at a constant speed (equal to speed of light), it can be used in conjunction with time duration for wave motion. The same object can be tracked using radar and the distance it travels over a given time period can be used to find its speed. Generally air traffic control (at the airports) and armed forces use radar.
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