After completing the assigned reading, answer each question below in the space provided.  When you are done with all of the questions, click on the "Submit Answers" button at the bottom of the page.

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1.  Answer BOTH of these questions in the space below:

A)  What kind of wave is sound?

B)  What form do sound waves have?

2.  How does sound spread through a uniform medium?

3.  Answer BOTH of these questions in the space below:

A)  What is the minimum intensity in watts per meter squared that a sound must have in order to be heard?

B)  What pressure in Neutons per meter squared does this correspond to?

4.  What is the audible frequency range?

5.  In what units is relative intensity or noise level measured?

6.  Why should people be careful to protect their eardrums against loud sounds?

7.  Answer BOTH of these questions in the space below:

A)  What is the apparent frequency shift of a passing whistle or horn called?

B)  What causes this shift?

8.  What three factors affect the speed of sound in water?

9.  What does the Doppler effect enable a sonar technician to do when analyzing returning sonar echoes from a submarine?

10.  What are two  modes of operation of shipboard sonar systems?

11.  Why do submarines rarely use active sonar?

12.  How do helicopters use sonar to detect submarines?