If the sonar transducer is stationary in the water
train came forward, the pitch of the whistle sounded
and sends out a ping of 10 kHz, the particles all send
higher to the occupants of the car. In the same way,
back a sound that has the same pitch. Now suppose
the particles “hear” a higher note and reflect this
that the transducer acquires forward motion and a
higher note. Therefore, the sonar equipment will
ping is sent out dead ahead. It is just as if the
detect a higher note than the one sent out. If the
transducer were the oncoming train, and the particles
transducer in this example is pointed dead astern, a
were occupants of the car. Remember, that as the
lower note than the one sent out will be heard.
Figure 46-Doppler effect. A. One-second audio signal. B. One sine wave of the audio signal.
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