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physics Advanced Subsidiary (AS) Level Physics.
 
Solved problems for the chapter:
 

Doppler Effect of Sound Waves

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Example 1.

A motorboat travels on water at a speed of 43 km/h. The waves caused by the boat form an angle of 50 degrees. What is the speed of the waves?

    
Example 2.

A train travels uniformly at a speed of 100 km/h. It emits a tone of 450 Hz with a siren. What frequency is heard by a stationary observer by the rail track before the train reaches him and when the train moves away from him? The speed of sound is 340 m/s.

    
3.

The car moving at a speed of 80 km/hr, is approaching a stationary siren emitting a tone at a frequency of 500 Hz. What frequency does a passenger in the car hear as it approaches and moves away from the source of the sound? The speed of sound in air is 340 m/s.

    
4.

At what speed must we approach a stationary sound source in order to hear an octave-higher tone (twice the sound frequency)?

    
5.

An ambulance with its siren on is approaching a tall building at a speed of 80 km/h. The siren emits a sound with a frequency of 400 Hz. The sound bounces off the building back towards the ambulance. What frequency of the reflected sound does the ambulance driver hear?

    
6.

Waves with a frequency of 0.1 Hz and a wavelength of 50 m travel at sea level. A motorboat travels at a speed of 10 m/s against the waves. With what frequency do the waves hit the boat? What is the relative speed of the boat with respect to the waves?

    
7.

A car is traveling at a speed of 36 km/h when an ambulance with its siren on approaches it from behind at a speed of 90 km/h. The siren emits a tone with a frequency of 400 Hz. What frequency does the car driver hear if:

  • there is no wind?

  • the wind blows in the direction of travel of both vehicles at a speed of 20 m/s?

  • both vehicles are stationary and only the wind is blowing?

The speed of sound in the air is 340 m/s.

    
8.

A car approaches a stationary listener at a speed of 72 km/h and emits a tone of 600 Hz. At the same time, another car moves away from the stationary listener at a speed of 54 km/h and emits a tone of unknown frequency. What is this unknown frequency if the stationary listener hears a tone of the same frequency from both cars? What frequency of the tone is heard by the stationary listener? The speed of sound is in air 340 m/s.

    

9.

An airplane flies at twice the speed of sound. What is the angle at the top of the Mach cone?

    
10.

A loudspeaker is attached to a cord 0.6 m long and waved horizontally at a frequency of 2 Hz. The speaker emits a tone with a frequency of 800 Hz. What are the maximum and minimum frequencies heard by a distant stationary listener? The speed of sound is 340 m/s.