Submarine problem

1. Aug 31, 2005

Vanity

Hi,

I need to solve this problem but I have no idea where to start. I made a little drawing with all the informations I have but now I'm stuck. Here's the problem:

A submarine uses sonar waves, to identify other ships, by directing a highly directional acoustic pulse at a target, and computing the time duration between the transmission of the "ping", and the return of the echo. If a sub is a depth of 500m and receives a ping return in 5.6s, determine the direct distance to the ship.

I'm not looking for the answer, just a little hint of what to start with. Thanks alot !

- alex.

2. Aug 31, 2005

Staff: Mentor

What's the speed of sound in water? How far must the sound have traveled in 5.6s? (Don't forget that the sound makes a round trip.)

3. Aug 31, 2005

Vanity

Great ! Thanks. One last question, does the temperature affects anything ? Thanks !

4. Aug 31, 2005

Staff: Mentor

Both pressure and temperature will affect the speed of sound. (But I'll bet you can ignore such complications.)

5. Aug 31, 2005

Vanity

The problem actually include the temperature, so I guess I need to include it in my formula. I google'd for it but could only find tables. If density of water is 1, what formula should I use ?

Thanks !

6. Aug 31, 2005

Staff: Mentor

Unless this problem is meant to exercise your detailed understanding of the speed of sound in a liquid (the speed depends on the bulk modulus and density, which in turn depend on pressure and temperature), I would just look up the speed of sound (in seawater... salinity counts!) at some standard temperature. That should be good enough.