MCAT Question A Day - 4/6/14 - Answer!

The depth of water in the ocean is determined by using sonar signals. Assuming that the speed of sound in water is about 1.5 km/s, and it takes a total of 6 s for a sonar signal to return to the ship after being emitted, what is the estimated depth of the ocean at that point?

A. 3.0 km

B. 9.0 km

C. 0.25 km

D. 4.5 km

The correct answer is (D). Six seconds represent the round-trip time of the sonar signal. Therefore, it takes 3 s for a signal traveling at 1.5 km/s to reach the ocean floor. Since distance equals speed times time,

(1.5 km/s) * 3s = 4.5km

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