#### BuBbLeS01

1. Homework Statement
My home is exactly 7.8 km from the Stadium where the 4th of July fireworks are held. The time difference between when I see a flash and when I hear the corresponding sound is 22.4073542085608 s. What is the temperature (in degrees Celsius) of the air?

2. Homework Equations
Vsound = sqrt (GAMMA * R * T) / M

3. The Attempt at a Solution
T = 20 degrees Celsius + 273 = 293
V = 7800/22.4073542085608 = 348.1 m/s

T = Vsound^2 * M / GAMMA * R

But I don't know M, GAMMA, or R???

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Staff Emeritus

#### Doc Al

Mentor
The time difference between when I see a flash and when I hear the corresponding sound is 22.4073542085608 s.
With 16 significant figures, whoever devised this problem has a sense of humor.

Nonetheless...

R is a universal constant; gamma and M are constants specific to air. Read all about it here: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe3.html#c1"

Astronuc beat me to it!

Last edited by a moderator:

#### BuBbLeS01

lol I know I love the 16 sig figs. So I understand that...but she showed us this way...
T = ((vsound - 331 m/s) / 0.6 m/s) °C
= ((348.1 m/s - 331 m/s) / 0.6 m/s) °C
= 28.5 °C

And I am don't know where she got that equation and some of the numbers from?

#### Doc Al

Mentor
And I am don't know where she got that equation and some of the numbers from?
The link I provided derives that exact equation.

#### BuBbLeS01

oh yea I am sorry I didn't scroll down.

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