## Sounds of Music C

Giantpants
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### Re: Sounds of Music C

linzhiyan wrote:
October 21st, 2019, 2:32 pm
1. An airplane is flying at a height of 11,000 m. Given that the temperature outside the airplane is -56.5ºC, what is the speed of sound outside the airplane?
2. Given the frequency of A3 is 250 Hz, what is the frequency of C4?
1. 297 m/s
2. 297 Hz again? Lol
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### Re: Sounds of Music C

Giantpants wrote:
October 26th, 2019, 3:58 am
linzhiyan wrote:
October 21st, 2019, 2:32 pm
1. An airplane is flying at a height of 11,000 m. Given that the temperature outside the airplane is -56.5ºC, what is the speed of sound outside the airplane?
2. Given the frequency of A3 is 250 Hz, what is the frequency of C4?
1. 297 m/s
2. 297 Hz again? Lol
I agree with 2, but I got 295 m/s for 1... (You may want to check my work because uhh... yeah lol)
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### Re: Sounds of Music C

Depends on your formula. I got 297 m/s using the simplified 331+0.6(temp) formula and I got 295 m/s using the more exact formula that includes the square root (c = 331.3 × √ (1 + (ϑ / 273.15)))
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### Re: Sounds of Music C

I used the simplified formula, but it’s good to know about the other too!

Anyway, what is the speed of sound in a material with a bulk modulus of elasticity of 9.4 E8 N/m^2, and a density of 270 kg/m^3?

EDITS: Just realized it said M/m^2 for like two months. Oops. Anyway rip this question marathon sorry D:
Last edited by Giantpants on January 18th, 2020, 12:26 pm, edited 2 times in total.
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### Re: Sounds of Music C

Giantpants wrote:
November 5th, 2019, 6:45 am
I used the simplified formula, but it’s good to know about the other too!

Anyway, what is the speed of sound in a material with a bulk modulus of elasticity of 9.4 E8 N/m^2, and a density of 270 kg/m^3?

EDITS: Just realized it said M/m^2 for like two months. Oops. Anyway rip this question marathon sorry D:
The speed of sound is $c = \sqrt{\frac{K_s}{\rho}}$ where $K_s$ is the bulk modulus of elasticity and $\rho$ is the density. This calculates to c = 1.9 km/s.
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### Re: Sounds of Music C

bernard wrote:
January 28th, 2020, 11:15 am
Giantpants wrote:
November 5th, 2019, 6:45 am
I used the simplified formula, but it’s good to know about the other too!

Anyway, what is the speed of sound in a material with a bulk modulus of elasticity of 9.4 E8 N/m^2, and a density of 270 kg/m^3?

EDITS: Just realized it said M/m^2 for like two months. Oops. Anyway rip this question marathon sorry D:
The speed of sound is $c = \sqrt{\frac{K_s}{\rho}}$ where $K_s$ is the bulk modulus of elasticity and $\rho$ is the density. This calculates to c = 1.9 km/s.
Yep, looks good! Your turn I guess? Lol or whoever else wants to go can.
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### Re: Sounds of Music C

I'll write a quick one:

I'm walking into school one morning at 1.5 m/s when my friend Spencer, standing on the other side of the auditorium lobby, decides it would be a good idea to take off Naruto running at 2.5 m/s in my direction while screaming an equally-tempered E5. Just another morning at TJ.

Note: Assume c = 343 m/s.

a. What frequency do I hear his shrieking as?
b. What pitch is this?
c. Is it sharp or flat?
d. How many (to the nearest 0.1) cents sharp or flat is this?

Bonus: What two instruments does Spencer play?
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### Re: Sounds of Music C

smayya337 wrote:
January 30th, 2020, 6:09 pm
I'll write a quick one:

I'm walking into school one morning at 1.5 m/s when my friend Spencer, standing on the other side of the auditorium lobby, decides it would be a good idea to take off Naruto running at 2.5 m/s in my direction while screaming an equally-tempered E5. Just another morning at TJ.

Note: Assume c = 343 m/s.

a. What frequency do I hear his shrieking as?
b. What pitch is this?
c. Is it sharp or flat?
d. How many (to the nearest 0.1) cents sharp or flat is this?

Bonus: What two instruments does Spencer play?
a. Doppler effect for APPROACHING objects: $f'=f\frac{v+v_o}{v-v_s}$
An equal-tempered E5 is 659.3 Hz.
Plug and chug:
$f'=659.3(\frac{343+1.5}{343-2.5})$
$f'=667.05Hz$
b. This is still an E5
c.  It is sharp
d. Cents equation: $c = 1200*log_2(\frac{f_1}{f_2})$
Plug and chug:
$c = 1200*log_2(\frac{667.05}{659.3})$
$c = 20.23 cents$

As for the bonus ...I would guess either the piccolo trumpet or piccolo, and I'd probably throw in the recorder as well lol

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### Re: Sounds of Music C

Nydauron wrote:
February 27th, 2020, 7:24 pm
smayya337 wrote:
January 30th, 2020, 6:09 pm
I'll write a quick one:

I'm walking into school one morning at 1.5 m/s when my friend Spencer, standing on the other side of the auditorium lobby, decides it would be a good idea to take off Naruto running at 2.5 m/s in my direction while screaming an equally-tempered E5. Just another morning at TJ.

Note: Assume c = 343 m/s.

a. What frequency do I hear his shrieking as?
b. What pitch is this?
c. Is it sharp or flat?
d. How many (to the nearest 0.1) cents sharp or flat is this?

Bonus: What two instruments does Spencer play?
a. Doppler effect for APPROACHING objects: $f'=f\frac{v+v_o}{v-v_s}$
An equal-tempered E5 is 659.3 Hz.
Plug and chug:
$f'=659.3(\frac{343+1.5}{343-2.5})$
$f'=667.05Hz$
b. This is still an E5
c.  It is sharp
d. Cents equation: $c = 1200*log_2(\frac{f_1}{f_2})$
Plug and chug:
$c = 1200*log_2(\frac{667.05}{659.3})$
$c = 20.23 cents$

As for the bonus ...I would guess either the piccolo trumpet or piccolo, and I'd probably throw in the recorder as well lol

Sorry for not responding sooner! Yeah, that looks about right for a through d. For the bonus, Spencer is actually a pretty good trumpet player and arguably an even better pianist. He also sings (and probably plays the recorder too, it wouldn't surprise me). Your turn!
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### Re: Sounds of Music C

I am about to play the Bach Preludio in E Major in my lesson. I couldn't play by memory, so here is the sheet music on IMSLP. However, I forgot to tune. (I also didn't warm up silly me!) I start to play the beginning, and my teacher covered her ears to prevent them from bleeding out due to the horrible intonation. "STOP!! Did you even tune your strings?!" she repulsed, "Your E string is a quarter of a semitone flat!!!" (She has perfect pitch down to the cent )

a) How many cents was I off by?
b) Given that I started on the E string and that my left pinkie was in the correct place, what note did I play and at what frequency was it? (Big hint: the music is a good starting point!) (EVEN BIGGER HINT: my finger was placed on the string halfway between the nut and the bridge)
c) What is the interval of the first two notes of Bach's Preludio called?
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