## Crave The Wave B

UTF-8 U+6211 U+662F
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### Re: Crave The Wave B

RontgensWallaby wrote:
UTF-8 U+6211 U+662F wrote:Oops, um, said that wrong.
A sound wave of 8 dB travels 1 meter and ends up being 5 dB. What is the volume of the attenuated sound wave after 1.5 meters?

Oh, ok.

ANS

Hmm, I got
Possible ANS

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### Re: Crave The Wave B

Never mind. I used the cube of it. However, after considering my dumb mistake, I still got a different answer...

Ans

I think that is correct... Tell me if you agree.
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

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### Re: Crave The Wave B

RontgensWallaby wrote:Never mind. I used the cube of it. However, after considering my dumb mistake, I still got a different answer...

Ans

I think that is correct... Tell me if you agree.

Decibels are already exponential, so it turns more into the inverse proportion law. So: $d_1 p_1 = d_2 p_2$

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### Re: Crave The Wave B

UTF-8 U+6211 U+662F wrote:
RontgensWallaby wrote:Never mind. I used the cube of it. However, after considering my dumb mistake, I still got a different answer...

Ans

I think that is correct... Tell me if you agree.

Decibels are already exponential, so it turns more into the inverse proportion law. So: $d_1 p_1 = d_2 p_2$

OK, now I think I have it. Decibels are logarithmic, so I believe this is the way you'd do it...

Yet another possible explanation

I'm aware that my answer sounds really unrealistic but my calculations (I hope) are all correct and 8 dB is barely audible in the first place.
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

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### Re: Crave The Wave B

RontgensWallaby wrote:
UTF-8 U+6211 U+662F wrote:
RontgensWallaby wrote:Never mind. I used the cube of it. However, after considering my dumb mistake, I still got a different answer...

Ans

I think that is correct... Tell me if you agree.

Decibels are already exponential, so it turns more into the inverse proportion law. So: $d_1 p_1 = d_2 p_2$

OK, now I think I have it. Decibels are logarithmic, so I believe this is the way you'd do it...

Yet another possible explanation

I'm aware that my answer sounds really unrealistic but my calculations (I hope) are all correct and 8 dB is barely audible in the first place.

Now, I'm confused. Somebody post a question.

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### Re: Crave The Wave B

I'll make this one a bit easier.
What is the peak wavelength emitted by a blackbody with a temperature of 10000 K?
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

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### Re: Crave The Wave B

Just going to post the answer right here so that I don't forget it.

ANS
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr

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### Re: Crave The Wave B

Found another good question, this time it's not original. Comes from Physics for Scientists and Engineers with Modern Physics.
Astronauts are visiting Planet X. They take a 2.5m string with a mass of 5g and a 1kg mass tied to one end. On the planet, the astronauts fix one end of the string, horizontally extend it for 2m, hold it as shown in this picture (image1.masterfile.com/em_w/03/65/18/632-03651827em.jpg) after 2m, and allow the remaining .5 m with the mass tied to it to hang freely. The astronauts then proceed to pluck the 2m long string, finding that the string forms a standing wave at 64 Hz and at 80 Hz but at no frequencies in between. What is the gravitational acceleration on Planet X?

A useful formula: v=root(T/d) where v is the speed of a wave on a string, T is the tension in millinewtons, and d is the linear density in grams per meter.
Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it. - Niels Bohr