Formative 9EF: Doppler Effect & Mediums

When a source of sound waves is moving relative to a stationary listener, there is a change in the frequency of the sound waves. The change in frequency affects the perceived pitch of the sound, resulting in the Doppler effect. An ambulance moving in between two observers is shown. Which choice correctly completes the model from the stimulus?

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GA.SPS9.e.

When a source of sound waves is moving relative to a stationary listener, there is a change in the frequency of the sound waves. The change in frequency affects the perceived pitch of the sound, resulting in the Doppler effect. An ambulance moving in between two observers is shown. Which observer will hear the highest pitch?

• Observer A, because the sound wave has a higher frequency as it is moving away

• Observer A, because the sound wave has a lower frequency as it is moving away

• Observer B, because the sound wave has a higher frequency as it is approaching

• Observer B, because the sound wave has a lower frequency as it is approaching

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GA.SPS9.e.

The table shows the speed at which sounds pass through various materials. Which material does sound pass through the slowest?

• rubber

• air

• glass

• aluminum

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GA.SPS9.d.

Sound travels fastest through (a)   and slowest through (b)   . This means that sound would reach a person quickest if they were listening through ​ ​ (c)  

• diamond
• air
• glass
• ice
• liquid water
• vegetable oil

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GA.SPS9.d.

A police car emits a siren at a constant frequency. Two observers can hear the siren. Their positions are shown on the diagram. How is the sound heard by observer X compared to observer Y? 

• The sound heard by observer X has a lower pitch.

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  The sounds heard by both observers have a lower pitch than the emitted sound.

• The sounds heard by both observers have the same pitch as the emitted sound.

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  The sound heard by observer X has a higher pitch.

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GA.SPS9.e.

The model shows a train leaving point A and approaching point B. Which statement best describes a change in the sound wave associated with the Doppler effect?

• The wavelength becomes shorter as the train approaches point B.

• The energy of the wave decreases as the train approaches point B.

• The pitch of the wave becomes lower as the train approaches point B.

• The frequency of the wave decreases as the train approaches point B.

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GA.SPS9.e.

The data table shows the speed of sound in air at different temperatures. Which best describes the relationship between air temperature and the speed of sound?

• Sound waves travel faster at lower temperatures because the molecules collide more.

• Sound waves travel at the same speed because the speed of sound is a constant.

• Sound waves travel faster at higher temperatures because the molecules move rapidly.

• Sound waves travel at a slower speed at higher temperatures because the molecules are spread out.

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GA.SPS9.d.

A student creates a model of a sound wave coming from an object that is moving toward an observer to demonstrate the Doppler effect. Using the model, which statement best describes the changes in the sound wave as it approaches the observer?

• The wavelength becomes longer and the pitch becomes lower.

• The wavelength becomes longer and the pitch becomes higher.

• The wavelength becomes shorter and the pitch becomes lower.

• The wavelength becomes shorter and the pitch becomes higher.

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GA.SPS9.e.

Echolocation is used by some animals, such as whales and bats, to find the location of objects by sending out sound waves through a medium. The length of time it takes for the sound wave to strike an object and bounce back tells the location of the object.

How would the length of time it takes a sound wave to return to a whale differ from the time it takes a sound wave to return to a bat?

• A sound wave would return faster to a bat because sound travels faster in air than it does in water.

• A sound wave would return faster to a bat because the wavelength is shorter in air than in water.

• A sound wave would return faster to a whale because sound travels faster in water than it does in air.

• A sound wave would return faster to a whale because the wavelength is longer in water than in air.

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GA.SPS9.d.

The picture shows an airplane traveling at the speed of sound. Which diagram most likely shows the sound waves associated with a plane traveling at the speed of sound?

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GA.SPS9.e.