## Sounds of Music C

SciolyMaster
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### Sounds of Music C

Ok I'm bored so here goes nothing

1. What is the beat frequency that results from the interference of two sounds with frequencies 400.0 Hz and 420.0 Hz?
2. You measure a sound's intensity as 90.0 dB at 4.00 m away from the source. What is its intensity in W/m^2?
3. What would be the intensity in dB of the above sound at 12.00 m from the source?

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UTF-8 U+6211 U+662F
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### Re: Sounds of Music C

SciolyMaster wrote:
September 13th, 2020, 11:50 am
Ok I'm bored so here goes nothing

1. What is the beat frequency that results from the interference of two sounds with frequencies 400.0 Hz and 420.0 Hz?
2. You measure a sound's intensity as 90.0 dB at 4.00 m away from the source. What is its intensity in W/m^2?
3. What would be the intensity in dB of the above sound at 12.00 m from the source?
```1) 20.0 Hz
2) 10^-3 W/m^2 (I'm using 10^-12 W/m^2 as 0 dB, but that may not be right?)
3) 10.0 dB```
Last edited by UTF-8 U+6211 U+662F on October 11th, 2020, 6:19 am, edited 1 time in total.

builderguy135
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### Re: Sounds of Music C

UTF-8 U+6211 U+662F wrote:
October 11th, 2020, 6:19 am
SciolyMaster wrote:
September 13th, 2020, 11:50 am
Ok I'm bored so here goes nothing

1. What is the beat frequency that results from the interference of two sounds with frequencies 400.0 Hz and 420.0 Hz?
2. You measure a sound's intensity as 90.0 dB at 4.00 m away from the source. What is its intensity in W/m^2?
3. What would be the intensity in dB of the above sound at 12.00 m from the source?
```1) 20.0 Hz
2) 10^-3 W/m^2 (I'm using 10^-12 W/m^2 as 0 dB, but that may not be right?)
3) 10.0 dB```
Wouldn't it be (10^-3)/9 = 0.000111 W/m^2 = 80.5dB?
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UTF-8 U+6211 U+662F
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### Re: Sounds of Music C

builderguy135 wrote:
October 13th, 2020, 6:59 am
UTF-8 U+6211 U+662F wrote:
October 11th, 2020, 6:19 am
SciolyMaster wrote:
September 13th, 2020, 11:50 am
Ok I'm bored so here goes nothing

1. What is the beat frequency that results from the interference of two sounds with frequencies 400.0 Hz and 420.0 Hz?
2. You measure a sound's intensity as 90.0 dB at 4.00 m away from the source. What is its intensity in W/m^2?
3. What would be the intensity in dB of the above sound at 12.00 m from the source?
```1) 20.0 Hz
2) 10^-3 W/m^2 (I'm using 10^-12 W/m^2 as 0 dB, but that may not be right?)
3) 10.0 dB```
Wouldn't it be (10^-3)/9 = 0.000111 W/m^2 = 80.5dB?
Not sure what you mean here, but a drop of 10 dB corresponds to dividing the intensity by 10..
Last edited by UTF-8 U+6211 U+662F on October 13th, 2020, 8:51 am, edited 1 time in total.

Umaroth
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### Re: Sounds of Music C

UTF-8 U+6211 U+662F wrote:
October 13th, 2020, 8:51 am
builderguy135 wrote:
October 13th, 2020, 6:59 am
UTF-8 U+6211 U+662F wrote:
October 11th, 2020, 6:19 am
```1) 20.0 Hz
2) 10^-3 W/m^2 (I'm using 10^-12 W/m^2 as 0 dB, but that may not be right?)
3) 10.0 dB```
Wouldn't it be (10^-3)/9 = 0.000111 W/m^2 = 80.5dB?
Not sure what you mean here, but a drop of 10 dB corresponds to dividing the intensity by 10..
No, he is correct. Decibels are a measure of intensity level, not intensity. Intensity is measured in W/m^2, which means you must convert decibels to W/m^2 first, then divide by 9, then convert back to decibels.
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UTF-8 U+6211 U+662F
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### Re: Sounds of Music C

Umaroth wrote:
October 13th, 2020, 10:10 am
UTF-8 U+6211 U+662F wrote:
October 13th, 2020, 8:51 am
builderguy135 wrote:
October 13th, 2020, 6:59 am

Wouldn't it be (10^-3)/9 = 0.000111 W/m^2 = 80.5dB?
Not sure what you mean here, but a drop of 10 dB corresponds to dividing the intensity by 10..
No, he is correct. Decibels are a measure of intensity level, not intensity. Intensity is measured in W/m^2, which means you must convert decibels to W/m^2 first, then divide by 9, then convert back to decibels.
Oops I thought he was talking about b yeah c I meant to subtract 90 by 10log 9, my bad.

Assuming it's my turn to go, define syntonic comma and give the ratio associated with it.
Last edited by UTF-8 U+6211 U+662F on October 13th, 2020, 12:08 pm, edited 2 times in total.

UTF-8 U+6211 U+662F
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### Re: Sounds of Music C

On second thought, this might be too in-depth a question to ask for this event, so here's another question:

What's the leading tone in the key of C minor?

nobodynobody
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### Re: Sounds of Music C

UTF-8 U+6211 U+662F wrote:
October 13th, 2020, 1:11 pm
On second thought, this might be too in-depth a question to ask for this event, so here's another question:

What's the leading tone in the key of C minor?
B
Last edited by nobodynobody on October 15th, 2020, 5:15 am, edited 3 times in total.
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### Re: Sounds of Music C

nobodynobody wrote:
October 13th, 2020, 6:25 pm
UTF-8 U+6211 U+662F wrote:
October 13th, 2020, 1:11 pm
On second thought, this might be too in-depth a question to ask for this event, so here's another question:

What's the leading tone in the key of C minor?
`B`
Yep! Make sure to use

Code: Select all

``[answer]``

Last edited by UTF-8 U+6211 U+662F on October 13th, 2020, 6:41 pm, edited 1 time in total.

nobodynobody
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### Re: Sounds of Music C

Hello, sorry for being late!

Consider a massless pendulum with a length of 1.29 meters and a mass of 40.3 kg.

a) What is the period of the pendulum on earth (acceleration of 9.8)?
b) What is the period of the pendulum on the moon (acceleration of 1.62)?
c) If the string suspending the mass had a mass of 10.0kg, what is the new period(on earth)?
d) If the mass was removed (from question c), what is the new period of the pendulum, if it were on the moon?
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