Chapter 17 Sample Problems
83. The sound intensity is 0.0080 W/m2 at 10 m from an
isotropic point source of sound.
(a) What is the power of the source?
(b) What is the sound intensity 5.0 m from the
source?
(c) What is the sound level 10 m from the source?
55. (easy version)
A sound source A moves towards a stationary
reflecting surface B. Relative to the air, the speed of
source A is 29.9 m/s. The speed of sound is 329
m/s. The source emits waves at a frequency of 1200
Hz as measured in the source frame.
In the reflector frame, what are the (a) frequency
and (b) wavelength of the arriving sound waves?
In the source frame, what are the (a) frequency and
(b) wavelength of the sound waves reflected back to
the source?
55. (hard version)
A sound source A and a reflecting surface B move
directly toward each other. Relative to the air, the
speed of source A is 29.9 m/s, the speed of surface
B is 65.8 m/s, and the speed of sound is 329 m/s.
The source emits waves at a frequency of 1200 Hz
as measured in the source frame.
In the reflector frame, what are the (a) frequency
and (b) wavelength of the arriving sound waves?
In the source frame, what are the (a) frequency and
(b) wavelength of the sound waves reflected back to
the source?