## 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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