Sound

[alice122]

A ship uses sonar to measure the depth of the seabed. The signals take 20s to return to the measuring device. Calculate the depth of the sea if the speed of sound in seawater is 1500 metres/second to the power -1

[jim360]

This is just a speed = distance/time calculation.

So we have that speed = 1500 metres/second, and time taken to reach the seabed must be (20/2)s = 10s.

So distance to bottom = speed*time = 1500(m/s)*10s = 15,000 m.

Since no sea is actually that deep, I'm wondering if there's something I've overlooked... or perhaps it's just a toy question.

[Peter Pedant]

.

He's right Alice - BUT perhaps you are like me and read 'return' to mean return journey only. in which case it is 3000m or 3km.

If you ask how long will it take for you to return from Glasgow
you dont say three hours going out and three hours coming back.....

as you can see - as a teenager I used to have real difficulty with these questions.

[vascop]

Check your maths Peter!!!!

[ll_billym]

20s for a sonar response from the seabed, I'd say the equipment is broken.

[Peter Pedant]

thank you vascop - dreaming I meant 7.5 Alice.

[ and V I hadnt been drinking - honest ]

[Graham-W]

Jim's calculation is correct. The deepest part of the Marianna Trench is only 11,000 metres. The 1,500 m/sec figure is about right for salt water. Are you sure the return time isn't 2.0secs?