An object is 10.64 km below the sea level. A research team sends down a sonar signal to confirm this depth. After how long can it expect to get the echo? Take speed of sound in sea water = 1520 m/s.

An object is 10.64 km below the sea level. A research team sends down

1.	An object is 10.64 km below the sea level. A research team sends down a sonar signal to confirm this depth. After how long can it expect to get the echo? Take speed of sound in sea water = 1520 m/s.
A.	21 s
B.	7 s
C.	14 s
D.	3.5 s
Answer» D. 3.5 s