# Calculating Doppler Effect: Bat Approaching Wall at 10 m/s & Squeaking at 80 kHz

• maccha
In summary, the wall will reflect the sound at the same frequency as it heard from the bat due to the reflection of sound waves.
maccha
A bat is approaching a wall. If it is traveling at 10 m/s and squeaks at 80 kHz, what frequency does it hear in its echo?

f=fo(1 +/- vo/v)
f=fo (1/(1 +/- vs/v))

So I got the right answer by initially making the wall the stationary "observer" and the bat the moving source, and finding the frequency the wall would "hear". Then I made the bat the moving observer and the wall the stationary source- for the frequency emitted by the wall, I used the frequency I found in the first step. I just want to confirm that this makes sense because I feel like I only got the answer by trial and error-so would the wall in fact reflect the sound at the frequency it "heard" from the bat and why?

Yes, the wall would reflect the sound at the frequency it heard from the bat. This is because sound is a wave and waves can be reflected off of surfaces. The frequency of the reflected sound is determined by the frequency of the original sound, so the wall will reflect the sound at the same frequency as it heard from the bat.

Yes, your approach of considering both the bat and the wall as either the moving source or the moving observer is correct. This is because the Doppler Effect is dependent on the relative motion between the source and the observer. In this case, the wall is acting as the stationary source and the bat as the moving observer, so the frequency of the echo heard by the bat will be dependent on its velocity compared to the velocity of sound. Similarly, when the bat is considered as the stationary observer and the wall as the moving source, the frequency of the sound emitted by the wall will be dependent on its velocity compared to the velocity of sound. Both of these frequencies will be different due to the Doppler Effect. The wall will reflect the sound at the frequency it "heard" from the bat because the frequency of the reflected sound is dependent on the frequency of the incident sound and the relative motion between the source and the observer.

## What is the Doppler effect?

The Doppler effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It is commonly observed with sound waves, such as the change in pitch of a siren as an ambulance passes by.

## How does the Doppler effect work?

The Doppler effect is caused by the relative motion between the wave source and the observer. If the source and observer are moving towards each other, the frequency of the wave appears higher. If they are moving away from each other, the frequency appears lower. This is due to the compression or stretching of the wave as it reaches the observer.

## What is the difference between the Doppler effect for sound waves and light waves?

The Doppler effect for sound waves is the change in pitch, while for light waves, it is the change in color. This is because sound waves travel through a medium, such as air, while light waves do not require a medium and can travel through a vacuum.

## How is the Doppler effect used in real life?

The Doppler effect has many practical applications, such as in weather radar systems, where it is used to measure the speed and direction of moving objects, like rain or wind. It is also used in medical ultrasound technology to measure blood flow and in astronomy to study the motion of stars and galaxies.

## What are some limitations of the Doppler effect?

One limitation of the Doppler effect is that it only applies to waves that are moving in a straight line. It also assumes that the source and observer are moving at constant speeds and in a straight line relative to each other. Additionally, the Doppler effect is not applicable for objects moving at speeds close to the speed of light.

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