| A | B |
|---|
| A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. She hears the echo 1.5 s after shouting. Estimate the length of the lake. | ??? |
| A sailor strikes the side of his ship just below the waterline. He hears the echo of the sound reflected from the ocean floor directly below 2.0 s later. How deep is the ocean at this point? | ??? |
| Calculate the wavelengths in air at 20 degrees Celsius for sounds in the maximum range of human hearing, 20 Hz to 20,000 Hz. | ??? |
| What is the wavelength of a 10-MHz ultrasonic wave? | ??? |
| What is the intensity of sound at the pain level of 120 dB? Compare it to that of a whisper at 20 dB. | ??? |
| What is the intensity level of a sound whose intensity is 2.0 x 10^-6 W/m^2? | ??? |
| A single mosquito 5.0 m from a person makes a sound close to the threshold of human hearing (0 dB). What will be the intensity level of 1000 such mosquitoes? | ??? |
| In audio and communications systems, the gain, B, in decibels is defined as B = 10 log (Pout/Pin), where Pin is the power input to the system and Pout is the power output. A particular stereo amplifier puts out 100 W of power for an input of 1 mW. What is its gain in dB? | ??? |
| The A string on a violin has a fundamental frequency of 440 Hz. The length of the vibrating portion is 32 cm and has a mass of 0.35 g. Under what tension must the string be placed? | ??? |
