:eek: standing waves where to begin

In summary, a person walks from one loudspeaker to the other and hears a beat frequency of 3.3 Hz. The frequency of the speaker towards which the person is moving will have an observed increase, and the other will have an observed decrease, from the nominal 438 Hz.
  • #1
mayo2kett
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Two loudspeakers face each other, vibrate in phase, and produce identical 438-Hz tones. A listener walks from one speaker toward the other at a constant speed and hears the loudness change (loud-soft-loud) at a frequency of 3.3 Hz. The speed of sound is 343 m/s. What is the walking speed?
 
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  • #2
Have you studied beats yet?

cookiemonster
 
  • #3
beat frequency

we are just starting beats now but my homework assignment is due sunday night, which is the day before the lecture on standing waves and beats...so far I've been reading and understand that 3.3Hz are the beats per second which is the beat frequency... and i probably need to use the equations f1=v/2L and v = lamda f to calculate something but I'm just not sure where to put everything...
 
  • #4
mayo2kett said:
Two loudspeakers face each other, vibrate in phase, and produce identical 438-Hz tones. A listener walks from one speaker toward the other at a constant speed and hears the loudness change (loud-soft-loud) at a frequency of 3.3 Hz. The speed of sound is 343 m/s. What is the walking speed?
Use doppler shift. The frequency is frame dependent. The difference in the observed frequencies of the two speakers will be the beat frequency. The frequency of the speaker towards which the person is moving will have an observed increase, and the other will have an observed decrease, from the nominal 438 Hz.
 
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  • #5
any help would me much appreciated... the assignment is due tonight
thanks :)
 
  • #6
i think i got the answer using the equation f' = ((v + vo)/(v- vs))*f which is the same as the equation f'=(1+u/v)f since in my case the source isn't moving... i was wondering if someone could check this for me to see if i was right... i have 3.3Hz=(1+u/(343m/s))438Hz which when i multiply it out gives me 340.4m/s for the walking speed...
 

FAQ: :eek: standing waves where to begin

What is a standing wave?

A standing wave is a type of vibration that occurs when two waves with the same frequency and amplitude travel in opposite directions and interfere with each other. This interference causes certain points, known as nodes, to remain stationary while other points, known as antinodes, oscillate between maximum and minimum amplitude.

What are the properties of a standing wave?

The properties of a standing wave include the number of nodes and antinodes, the wavelength, the amplitude, and the frequency. These properties can be manipulated by changing the frequency or wavelength of the two interfering waves.

How are standing waves created?

Standing waves are created when two waves with the same frequency travel in opposite directions and interfere with each other. This can happen when a wave is reflected back upon itself, such as in a closed tube or on a string fixed at both ends.

What is the difference between a standing wave and a traveling wave?

The main difference between a standing wave and a traveling wave is that a standing wave remains in one place and does not transfer energy, while a traveling wave moves through a medium and transfers energy.

What are some real-world applications of standing waves?

Standing waves have various applications in fields such as acoustics, electronics, and optics. Some examples include musical instruments like guitars and violins, microwave ovens, and laser beams. Standing waves are also used in medical imaging techniques like ultrasound and MRI.

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