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## Homework Statement

A submarine on the ocean surface gets a sonar echo indicating an underwater object. The echo comes back at an angle of 20* above the horizontal and the echo took 2.32s to get back to the submarine. What is the object's depth?

## Homework Equations

delta of theta = (2pi/lambda) * (delta of L)

I = (P)/(4piR^2) and (I2/I1) = (R1/R2)^2

## The Attempt at a Solution

I really have no idea where to begin this problem. I can't really visualize it...if the submarine is on the ocean's surface and emits a sonar signal, shouldn't the echo be coming up from under the submarine vertically? Why is it 20* above the horizontal? I tried drawing a diagram but I don't know what it should look like with the information given. Also, I have no idea what equation would be best to use either. (I have more equations, I just thought that these would be the most helpful for the problem.)

## Homework Statement

A person has a hearing loss of 30dB for a particular frequency. What is the sound intensity that is heard at this frequency that has an intensity of the threshold of pain?

## Homework Equations

same I equations as above and B = 10log(I/Io)

Ip = 1.0W/m^2

## The Attempt at a Solution

Here is what I did:

log (I / 1.0W/m^2) = 3B

I = 10^3 W/m^2

Am I totally off on what the question is asking me to do?

THANKS!