1. At a rock concert, a dB meter registered 124 dB when placed 2.5 m in front of a loudspeaker on stage. What is the sou

[answerhappygod]

1. At a rock concert, a dB meter registered 124 dB when placed
2.5 m in front of a loudspeaker on stage. What is the sound level
produced by the rock concert at 10 m, assuming uniform spherical
spreading of the sound and neglecting absorption in the air?
(I0 =
1 ´ 10−12 W/m2 is a
reference intensity, usually taken to be at the threshold of
hearing.)
129 dB
119 dB
112 dB
122 dB
109 dB
2. A train is approaching a station at a constant speed of
14 m/s. A station horn is sounded at a frequency of 530 Hz.
What will be the frequency heard by an observer riding the train?
Assume T = 25°C.
495 Hz
551 Hz
553 Hz
565 Hz
346 Hz