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Worksheet: The Doppler Effect

Q1:

What frequency is received by a mouse just before being dispatched by a hawk flying at it at 25.0 m/s and emitting a screech of frequency Hz? Take the speed of sound to be 331 m/s.

  • A
  • B
  • C Hz
  • D
  • E

Q2:

A commuter train approaches a crossing and blows its horn to make a note of frequency 200 Hz. An observer at the crossing measures the frequency of the train’s horn as 208 Hz. The speed of sound in the train’s vicinity is 335 m/s.

What is the speed of the train?

If the train’s speed remains constant, what frequency does the observer measure as the train recedes from them?

Q3:

An ambulance with a siren blaring is approaching an accident scene. The ambulance is moving at 70.00 mph. A nurse is approaching the scene from the opposite direction, running at . What frequency does the nurse observe? Assume the speed of sound is .

Q4:

What is the minimum speed at which a source must travel toward you for you to be able to hear that its frequency is Doppler shifted? That is, what speed produces a shift of on a day when the speed of sound is 331 m/s?

Q5:

Two eagles fly directly toward one another, the larger eagle at a speed of 15.0 m/s and the smaller one at a speed of 20.0 m/s. Both eagles screech, the larger emitting a screech of frequency of Hz and the smaller one emitting a screech of frequency Hz. The speed of sound in the air around the eagles is 330 m/s.

What is the frequency of the screech heard by the larger eagle?

What is the frequency of the screech heard by the smaller eagle?

Q6:

Two cars have horns and each horn’s frequency is 800 Hz. The cars move toward one another, both sounding their horns. Car A is moving at 65.00 mph and Car B is at 75.00 mph. Use a value of 343 m/s for the speed of sound.

What is the beat frequency heard by Car A’s driver?

What is the beat frequency heard by Car B’s driver?