Question

A ship on the surface of water sends a signal and receives it back from a submarine inside water after 4 s. Calculate the distance of the submarine from the ship:
(The speed of sound in water is 1450 m/s)
A) 2.9 km
B) 2.5 km
C) 1.8 km
D) 3.2 km

Answer 1

In transmission of signals, we use either ground wave communication, sky wave communication or optical fibers or other means. In water we use SONARs and MASERS. Also, if the signal is of the form of EMW, then it will always travel in a straight line.

Complete step by step answer:
The signal is sent from the transmitter, it goes and touches the bed of the ocean and then it returns back. If x is the distance from the ship to the bottom of the sea, then the distance covered is 2x and time taken to cover 2x distance is 4s.
The relationship between speed, distance and time is given by the formula,
Distance= speed $\times$time
D = v $\times$t---(1)
Now If x is the distance from the ship to the bottom of the sea, then the distance covered is 2x
2x= v $\times$4
Given v= 1450 m/s
$\implies$ 2x= 1450 $\times$4
$\implies$ x= 2900 m
$\implies$ x= 2.9 km

so, the distance from the ship to the bed of the sea is 2.9km. Hence, the correct option is (A).

Additional information- While measuring the depth a device used called SONAR emits a signal or pulse of sound into the water. If an object is in the path of the sound pulse, the sound bounces off the object and returns an “echo” to the sonar transducer and at the transducer, the signal is converted into meaningful information.

Note- While measuring the depth of an ocean the instrument which is used for the purpose is called SONAR. SONAR stands for sound navigation ranging. It is widely used for measurement of depth and also for locating underwater bodies or wreckage of drowned ships