Doppler-ganger Game

doppelgänger: an apparition or double on a living person.

To play the Doppler-ganger Game you must describe the visual scenario of a doppler effect situation into English. In the end there will be two versions (visual and written) of the same doppler situation.

1) The car is parked and Person 1 and Person two are sitting on the sidewalk. The car horn goes off.

What frequency does Person 1 hear the horn compared to Person 2?

1. P1 < P22. P1 = P23. P1 > P24. No way to know

Person 1Stationary

Person 2Stationary

CarStationary

2) The car is driving and Person 1 and Person two are sitting on the sidewalk. The car horn goes continuously sounds.

What frequency does Person 1 hear the horn compared to Person 2?

1. P1 < P22. P1 = P23. P1 > P24. No way to know

Person 1Stationary

Person 2Stationary

CarDriving

3) The car is parked and Person 1 and Person two are sitting on the sidewalk. The car horn goes off.

What frequency does Person 1 hear the horn compared to the kids

1. P1 < P22. P1 = P23. P1 > P24. No way to know

Person 1Stationary

P2Stationary

CarStationary

4) The air temperature increases by 10oC on the second story. Describe the sound differences due to this temperature difference.

________________________________________________________________________________________________________________________

Person 1Stationary

Person 2Stationary

CarDriving

Explanations1. P1 = P2. The car is not moving and neither are the people. This means

that when the two people will hear the same frequency because there is no compression.

2. P1 > P2. The car is moving towards P1 and away from P2. This means that P1 is hearing compressed waves, increasing the perceived frequency of the car horn. P2’s waves are now even less frequent than in Q1 because the waves are “driving away” from them.

3. P1 = P2. P2 on skates and P1 sitting hear the same frequency because the waves aren’t moving at a different compression. P2 is just moving.

4. When there is a great temperature gradient, waves refract down towards the cooler air and greatly increase the range of the sound.