Question

3. Sound waves can be used to map the sea floor by timing how long it takes the echo to reach the surface of the water. A certain mapping ship uses 600 kHz ultrasound. A. What is the wavelength of the sound in the air and in the water? B. Sketch the ship sending out a pulse, the pulse bouncing off the sea floor, and returning to the ship. C. If the echo reaches the detector 0.52 s after the pulse is emitted, how far below the ship is the sea floor? D. How long would it take the echo to reach the ship if it bounced off the top of a formation that is 5 m higher than the sea floor?

Answer 1

A. The wavelenght is given by:

= V

The speed varies depending on the medium the sound is traveling through, in air its 340 m/s and in water in 1530 m/s approx

340m/s 567 x 10-4m Aair = 600000.-1 = 5.67 x 10-4m

1530m/s m ater 600000-1 = 2.55 x 10

B.

Receiver Sound Source reflected pulse emited pulse Sea floor

C. The depth can be calculated using:

2d = ut

d=1/2 x 1530m/s x 0.52s = 397.8m

D. In this case we can use the same equation but solving for time:

2d 2 x (397.8m - 5m) om) = 0.515 1530m/s 1520