Examples Answers
1. Assume that you shout toward a tall cliff directly in front of you and you hear the echo 3.0 seconds later. Estimate the distance to the cliff. Assume 20 degrees C and 1 atm.
2. Given that the intensity of a sound is 2.5x10-5 W/m2. What is the sound level? Use the minimum intensity audible to a good ear as the reference level.
3. Given that the frequency of a siren is 1500 Hz when stationary. Assume 20 degrees C and 1 atm.
a. What frequency would be detected if you move 25 m/s toward the siren?
b. What frequency would be detected if you move 25 m/s away from the siren?
4. How can we justify the statement that sound travels as a wave? What is the evidence?
5. How can we justify the statement that sound is a form of energy? What is the evidence? - start with a definition of energy... and work ...
6. You have probably experiments with or observed the use of the following simple "telephone". A string is attached to the bottom of 2 paper cups and a person speaking in
one can be heard by the other. Explain how this works. What kind of waves are being transmitted?
7. Is there a Doppler shift if both the source and observer move with the same velocity in the same direction?