1. Approximately how many times louder is a 130-dB sound than a 70-dB sound? (1,000,000 times more intense is incorrect)

2. An audio speaker producing a steady sound at an outdoor concert is 22 ft away from you. If you move to a position where the speaker is 65 ft distant, by what factor will the amplitude of the sound change?

\frac{A_f}}{A_i}=

3. The force stretching the D string on a certain guitar is 145 N. The string's linear mass density is 0.007 kg/m. What is the speed of waves on the string?

4. Ultrasound probes can resolve structural details with sizes approximately equal to the wavelength of the ultrasound waves themselves. What is the size of the smallest feature observable in human tissue when examined with 16-MHz ultrasound? The speed of sound in human tissue is 1,540 m/s.

5. A sound pulse emitted underwater reflects off a school of fish and is detected at the same place 0.17 s later (see the figure below). How far away are the fish? (Assume the water temperature is 20C.)