Calculate Intensity of Sound Wave at Cliff from Radio Source

In summary, Michelle is at a picnic and notices an echo from a cliff while playing music on her radio, which takes 1.2 seconds to return. With the speed of sound being 343 m/s, the cliff is approximately 206m away. However, the intensity of the music arriving at the cliff cannot be determined without knowing the distance between the radio and the cliff.
  • #1
kokenwa
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Homework Statement


Michelle is enjoying a picnic across the valley from a cliff. She is playing music on her radio (assume it to be an isotropic source) and notices an echo from the cliff. She claps her hands and the echo takes 1.2 s to return.
(a) Given that the speed of sound in air is 343 m/s on that day, how far away is the cliff?
-i got the correct answer for this one, and it was 206m


(b) If the intensity of the music 1.0 m from the radio is 1.0 10-5 W/m2, what is the intensity of the music arriving at the cliff?


i can't find the answer for b. can someone help me out?
 
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  • #2
Intensity is proportional to 1/r^2.

That is, if the source is twice as far away, the intensity is 1/4; three times as far away, 1/9 etc...
So if the source is 206 times as far away...?
 
  • #3
i put in 2.35 x 10^-5 and it was still wrong
 
  • #4
how did you get 2.35 x 10^-5 ? - show your working.

this is not what I got.
 

1. What is the formula for calculating the intensity of a sound wave?

The formula for calculating the intensity of a sound wave is I = P/A, where I is the intensity in watts per square meter (W/m^2), P is the power of the sound wave in watts (W), and A is the area through which the sound wave is passing in square meters (m^2).

2. How do you determine the distance from a radio source to a cliff?

The distance from a radio source to a cliff can be determined using the formula d = (c * t) / 2, where d is the distance in meters (m), c is the speed of sound in air (343 m/s), and t is the time it takes for the sound wave to travel from the radio source to the cliff.

3. What factors can affect the intensity of a sound wave at a cliff from a radio source?

The factors that can affect the intensity of a sound wave at a cliff from a radio source include the power of the radio source, the distance from the radio source to the cliff, and any obstacles or obstructions in the path of the sound wave.

4. How does the intensity of a sound wave change as it travels from a radio source to a cliff?

The intensity of a sound wave decreases as it travels from a radio source to a cliff due to the spreading out of energy over a larger area. This is known as the inverse square law, which states that the intensity of a sound wave is inversely proportional to the square of the distance from the source.

5. How can the intensity of a sound wave at a cliff from a radio source be measured?

The intensity of a sound wave at a cliff from a radio source can be measured using a sound level meter, which measures the sound pressure level in decibels (dB). The sound pressure level can then be converted to intensity using the formula I = 10^(L/10), where I is the intensity in W/m^2 and L is the sound pressure level in dB.

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