6 weeks 1 day
Enigma 2 / Depth of the Hess Deep Rift ?
Submitted by Jean-Luc Berenguer on Tue, 12/11/2012 - 05:43
Depth of the seafloor
In a few days the ship will operate in the Hess Deep Rift, a deep rift in the Pacific.
How we know how deep is it ?
Scientists use sound waves. The principle is simple, it is the echo. A sound pulse is emitted from the ship towards the bottom, where it is reflected and returns to the surface: scientists record its echo, and measure the travel time to go back.
It reminds me of the storm: We can evaluate the distance of the storm by counting the number of seconds between the vision of lightning and thunder, and multiplying this number by 300 (speed of sound = 300 m/s), we have the distance separating us from the storm in meters. We can hear 'the storm is at 7 seconds' to be translated by 'the storm is located three km far from us’ (300 x 7 = 2 100 m).
The researchers recorded a time of 7 seconds in Hess Deep Rift * to the path of the waves in the water.
The scientists will conclude:
1. The depth of the rift is 2 100 m
2. The depth of the rift is 1 050 m
3. The depth of the rift is 5 250 m
Answer to this enigma by a comment !
Solution next sunday ... on the blog.