Please HELP! No teacher! Physics sound unit!?

R

RickB

New member
I don't know what "I=P/A" is--but for this problem you'll have to use some algebra, and you'll have to know two facts:

1. Speed of sound through 0C air;
2. Speed of sound through 20C air.

I don't know what those speeds are (you'll have to look them up or use some formula that's in your book); but for now let's use these variables:

V0 = speed of sound through 0C air;
V20 = speed of sound through 20C air;
D0 = thickness of 0C layer;
D20 = thickness of 20C layer.

Now the time it takes for (anything) to go distance "D" when traveling at speed "V" is given by this formula:

Time = D/V

So, the time it takes for the sound to go through both layers is:

Total time = (time through 0C layer) + (time through 20C layer)
Total time = (D0/V0) + (D20/V20)

The problem tells you that the total time is 4.5 sec., so:

4.5 sec. = (D0/V0) + (D20/V20)

Also, the problem tells you that the total distance is 1500 meters. This is the sum of the thicknesses of the two layers, so:

1500 meters = D0 + D20

You now have two equations in two unknowns (D0 and D20). Use algebra to solve them simultaneously.
 
Please help me awnser this question. Please can you show your steps :P
*The sound from a very high burst of fireworks takes 4.5 s to arrive at your eardrums. THe burst occured 1500 m above you and travelled vertically though two stratified layers of air, the top one at 0C and the bottom one at 20C. How thick is each layer of air?

So I'm guessing I have to use I=P/A but I don't where to go from there...

Thanks in advance,

A
 
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