Physics
Examine the graph depicting the transmitted (T) and reflected (R) waves from submarines A and B, which are equipped with a device emitting ultrasonic sounds. Study the graph and answer the following. (Speed of sound in water is 1500 m/s)
(a) Name the device used here.
(b) Why is ultrasonic sound used in this device?
(c) Which submarine is closer to the ship? Calculate the distance of the closest submarine.
Sound
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Answer
(a) Sound Navigation and Ranging (SONAR)
(b) They are not easily absorbed by a medium and can travel undeviated over long distances in the form of a narrow, confined beam
(c) Submarine B is closer to ship, because reflection time R1 for submarine A = 50 s - 20 s = 30 s and reflection time R2 for submarine B = 60 s - 40 s =20 s.
Distance of closest submarine B
= 15000 m
= km
= 15 km
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