Doppler Effect 1

What would happen to a frequency that a listener hears when the source slows down as the source approaches the listener.

• Increase

• Decrease

• Remains the same

What would happen to a frequency that a listener hears when the source slows down as the source drives away from the listener.

• Increase

• Decrease

• Remains the same

An ambulance is travelling towards a hospital at a constant velocity of 30 m∙s-1.

The diagram above shows the wave fronts of the sound produced from the siren as a result of this motion.

At which side of the diagram, X or Y, is the hospital situated?

• X

• Y

Was the sound source moving TOWARDS or AWAY FROM the listener?

• Towards

• Away from

When the ambulance moves at a constant speed, a stationary observer detects a frequency that is lower than that emitted by the siren.Is the ambulance moving towards or away from the observer

• Towards

• Away

An ambulance is travelling towards a hospital at a constant velocity of 30 m∙s-1.The siren of the ambulance produces sound of frequency 400 Hz. Take the speed of sound in air as 340 m∙s-1.

Calculate the frequency of the sound of the siren heard by a person standing at the hospital.

• 400 Hz

• 501,43 Hz

• 478,32 Hz

• 438,71 Hz

An ambulance is moving towards a stationary listener at a constant speed of 30 m∙s-1. The siren of the ambulance emits sound waves having a wavelength of 0,28 m. Take the speed of sound in air as 340 m∙s-1.

Calculate the frequency of the sound waves emitted by the siren as heard by the ambulance driver.

• 1 331,80 Hz

• 1 214,29 Hz

• 1 335,72 Hz

• 1202,29 Hz

An ambulance is moving towards a stationary listener at a constant speed of 30 m∙s-1. The siren of the ambulance emits a frequency of 1 214,29 Hz. Take the speed of sound in air as 340 m∙s-1.

Calculate the frequency of the sound waves emitted by the siren as heard by the listener.

• 1 331,80 Hz

• 1 214,29 Hz

• 1 367,32 Hz

• 2 347,68 Hz

The siren of the ambulance produces sound of frequency 400 Hz. Take the speed of sound in air as 340 m∙s-1. Calculate the wavelength of the sound.

• 0.98 m

• 0.76 m

• 0,85 m

• 1.34 m

Use the information in the table to calculate the speed of sound during the investigation. Choose the closest option.

• $336,15m\cdot s^{-1}$

• $236,15m\cdot s^{-1}$

• $386,15m\cdot s^{-1}$

• $256,15m\cdot s^{-1}$