After giving an intense performance, a confused and disoriented flautist has wandered onto the motorway! They are playing a constant 300Hz on their flute and are essentially stationary If you are driving along the motorway at 100 km/h(27.8 m/s). What is the frequency you hear from the flautist's you hear from the flautist's instrument before you pass them and after you pass them?

Question

After giving an intense performance, a confused and disoriented flautist has wandered onto the motorway! They are playing a constant 300Hz on their flute and are essentially stationary If you are driving along the motorway at 100 km/h(27.8 m/s). What is the frequency you hear from the flautist's you hear from the flautist's instrument before you pass them and after you pass them?

Coincidently the horn on your car, which you sound as you narrowly miss the flautist in the problem above , also give a constant 300 Hz. tone. What frequency does the flautist hear before and after you pass them?

Answer 1

so for the first part of the question.. I used f=((C+Vr)/c)*fs for moving towards and when its moving away, the sign changes to negative instead of positive right?

But for the second part of the question,,, what formula do i use here? im a little confused here!

Answer 2

Flutist hears the difference or "beat" frequency

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/beat.html

Answer 3

To calculate the frequency you would hear from the flautist's instrument before and after passing them, you would need to consider the concept of the Doppler effect. The Doppler effect describes the change in frequency or pitch of a sound when either the source of the sound or the observer is in motion relative to each other.

Before we proceed with the calculations, let's establish a few parameters:

- Speed of sound in air: The speed of sound in air is approximately 343 meters per second at room temperature.

Now, let's calculate the frequency you would hear from the flautist's instrument before and after passing them.

1. Frequency heard before passing the flautist:
When the source (flautist) of the sound is stationary and the observer (you in the car) is moving towards the source, the frequency heard by the observer is higher than the emitted frequency. The formula to calculate the frequency heard before passing is given by:

f_observed = f_emitted * (v_sound + v_observer) / v_sound

Here:
- f_observed: Frequency heard by the observer (you in the car)
- f_emitted: Frequency emitted by the flautist (300 Hz in this case)
- v_sound: Speed of sound in air
- v_observer: Speed of the observer (you in the car, which is 27.8 m/s or 100 km/h)

Plugging in the values:
f_observed = 300 Hz * (343 m/s + 27.8 m/s) / 343 m/s

Calculating this expression, you would hear a frequency slightly higher than 300 Hz before passing the flautist.

2. Frequency heard after passing the flautist:
When the source (flautist) of the sound is stationary and the observer (you in the car) is moving away from the source, the frequency heard by the observer is lower than the emitted frequency. The formula to calculate the frequency heard after passing is given by:

f_observed = f_emitted * (v_sound - v_observer) / v_sound

Using the same values as before:
f_observed = 300 Hz * (343 m/s - 27.8 m/s) / 343 m/s

Calculating this expression, you would hear a frequency slightly lower than 300 Hz after passing the flautist.

Now, let's move on to the second part of the question: What frequency does the flautist hear before and after you pass them?

Since the flautist is stationary, the frequency they would hear is the same as the frequency they are emitting. Therefore, the frequency the flautist hears before and after you pass them is simply 300 Hz, regardless of your speed.

Remember, these calculations assume ideal conditions and neglect other factors that may affect the actual perceived frequency, such as air density changes or the direction of the sound relative to the observer.