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Published byBlanche McKenzie Modified over 9 years ago
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Imagine a bug jiggling its legs and bobbing up and down in the middle of a quiet puddle
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What would happen to the waves if the bug began to swim forward, toward B?
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What does that do to the frequency of the waves, in front of the bug and behind the bug? In front of the bug…the frequency ↑ Behind the bug…the frequency ↓
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http://www.fearofphysics.com/cgi- bin/doppler.cgi?dir=t&vs=200&mode=wrap http://www.fearofphysics.com/cgi- bin/doppler.cgi?dir=t&vs=200&mode=wrap
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Pitch…. A man’s vocal chords vibrate slower than a woman’s…hence a lower voice=lower pitch
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The Doppler effect causes the changing pitch of a siren In front of the car… the pitch ↑ Behind the car… the pitch ↓
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Note: The change in loudness is not the Doppler Effect! It is the shift in frequency! http://www.youtube. com/watch?v=Y5Kae CZ_AaY http://www.youtube. com/watch?v=Y5Kae CZ_AaY
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Police use the Doppler effect of radar waves to measure the speeds of cars on the highway
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2011, Aroldis Chapman reached back and threw a pitch to Andrew McCutchen of the Pirates. The pitch wound up being high and tight, not a location necessarily to be proud of, and yet he received a standing ovation. Why the standing ovation, you may ask? The stadium radar reading displayed a velocity of 106 MPH, a speed that has only been topped twice since baseball started recording pitch velocities.Pirates
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http://www.youtube.com/watch?v=Y5KaeCZ _AaY http://www.youtube.com/watch?v=Y5KaeCZ _AaY
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Named after Christian Doppler (Austrian) 1803-1853
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When a source moves toward you, do you measure an increase or decrease in wave speed? Neither! It is the frequency of a wave that undergoes a change, not the wave speed.
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How does the apparent frequency of waves change as a wave source moves? The sound waves become more frequent (compressed together). The sound waves become less frequent (stretched apart).
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