2. A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 44 dB by an observer 10 km away.
(a) What is the average power generated by the horn?
W
(b) What intensity level of the horn's sound is observed by someone waiting at an intersection 56 m from the train? Treat thehorn as a point source and neglect any absorption of sound by the air.
dB
3. An outside loudspeaker (considered a small source) emits sound waves with a power output of 110 W.
(a) Find the intensity 11.0 m from the source.
W/m2
(b) Find the intensity level in decibels at that distance.
dB
(c) At what distance would you experience the sound at the threshold of pain, 120 dB?
m