The physics application to speed guns
Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a radio signal in a narrow beam, then receive the same signal back after it bounces off the target object( baseball). Due to a phenomenon called the Doppler effect, if the object is moving toward or away from the gun, the frequency of the reflected radio waves when they come back is different from the transmitted waves. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced. This speed is given by the following equation:
c is the speed of light , f is the frequency that is emitted of the radio waves and Δf is the difference in frequency between waves that are emitted and waves that are received.
As a result as the pitcher throws the baseball the speed gun emits radio signals that bounce off the baseball , as the Doppler effects takes place the speed gun calculates the speed of the baseball from the waves that were reflected off the baseball.