How does sonar work?

1 Answer
Gió
May 11, 2016

This is a simplified version...

Explanation:

Consider the diagram:
enter image source here
A submarine sends a pulse of sound. After a while it receives an echo from a fish.

The operator on the submarine knows:
1) the speed of sound in water, #v_s#;
2) the time between the sending of the sound and the detection of the echo.

He can use the fact that speed is distance divided by time to evaluate the distance remembering that the sound described the two distances to go (1 in the diagram) and to come back (2 in the diagram); so we get:
#v_s=(2d)/t#
Rearranging we get that the fish will be at:
#d=(v_st)/2#

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