14.1 Speed of Sound, Frequency, and Wavelength
A bat produces a sound at and wavelength . What is the speed of the sound?
|Gases at 0 °C|
|Liquids at 20 °C|
|Solids (longitudinal or bulk)|
A sound wave with a frequency of 80 Hz is traveling through air at 0°C. The sound wave enters a block of aluminum. If the sound's frequency does not change, what happens to the sound's wavelength?
It's wavelength increases by a factor of 4.2.
It's wavelength increases by a factor of 18.
It's wavelength decreases by a factor of 4.2.
It's wavelength decreases by a factor of 18.
14.2 Sound Intensity and Sound Level
Calculate the sound intensity for a sound wave traveling through air at 15° C and having a pressure amplitude of 0.80 Pa. (Hint—Speed of sound in air at 15° C is 340 m/s .)
- 9.6×10−3 W / m2
- 7.7×10−3 W / m2
- 9.6×10−4 W / m2
- 7.7×10−4 W / m2
The sound level in dB of a sound traveling through air at is . Calculate its pressure amplitude.
14.3 Doppler Effect and Sonic Booms
An ambulance is moving away from you. You are standing still and you hear its siren at a frequency of 101 Hz. You know that the actual frequency of the siren is 105 Hz. Assuming the speed of sound is 331 m/s, what is the speed of the ambulance?
An ambulance passes you at a speed of 15.0m/s and its siren has a frequency of 995 Hz. Assuming the speed of sound in air is 331m/s, what is difference in the frequencies you perceive before and after it passes you?
14.4 Sound Interference and Resonance
What is the length of an open-pipe resonator with a fundamental frequency of ? (Assume the speed of sound is .)
An open-pipe resonator has a fundamental frequency of . By how much would its length have to be changed to get a fundamental frequency of ? (Assume the speed of sound is .)