A SONAR (sound navigation and ranging) uses ultrasonic waves to detect and locate objects under water. In a submarine equipped with a SONAR the time delay between generation of a probe wave and the reception of its echo after reflection from an enemy submarine is found to be 77.0 s. What is the distance of the enemy submarine? (Speed of sound in water = 1450 m/s).

Question

Philoid · Accepted Answer

Given,

Speed of sound in water = 1450 m/s

Total time taken for transmission = 77 s

Let distance between our submarine and enemy submarine be, D.

∴ Time taken to travel the distance D be, t = 0.5×77 = 38.5 s

Thus,

D = Speed of sound in water × Time taken to travel the distance D

= 1450×38.5 m

= 55.8 km