Assignment

1. An ambulance travels down a highway at a speed of 75.0 mi/h, its siren emitting sound at a frequency of 400 Hz. What frequency is heard by a passenger in a car travelling at 55.0 mi/h in the opposite direction as the car:
   1. Approaches?
   2. Moves away from the ambulance?
2. A train moving at a speed of 40.0 m/s sounds its whistle, which has a frequency of 500 Hz. Determine:
   • The frequency heard by a stationary observer as the train approaches the observer.
   • The frequency heard by the stationary observer as the train recedes from the observer.
3. A police car with its siren on (emitting at 600 Hz) is moving towards a stationary observer at a speed of 25.0 m/s. The speed of sound in air is 343 m/s.
   • What frequency does the observer hear as the car approaches?
   • What frequency is heard as the car passes and moves away from the observer?
4. A person is riding a bicycle at 10.0 m/s toward a stationary source of sound that emits a frequency of 300 Hz. The speed of sound is 340 m/s.
   • What frequency does the person hear while moving toward the source?
   • What frequency would they hear if they were moving away from the source at the same speed?
5. An observer is in a car moving at 20.0 m/s behind another car that is also moving in the same direction at 15.0 m/s. The car ahead is emitting a horn sound at 500 Hz. The speed of sound is 343 m/s.
   • What is the apparent frequency heard by the observer in the trailing car?
   • How would the frequency change if the observer’s car slowed to 10.0 m/s?