2) the Intensity Level of Sound from a Jet at 50 M Is 120 Db. What Is the Intensity Level At

Ch #16

Sound supplement

1) A person is listening to music 5 ft away. How many times more or less will the intensity be if you move

a) 10 ft from the source b) 20 ft c) 2.5 ft d) 1 ft e) 3.5 ft

2) The intensity level of sound from a jet at 50 m is 120 dB. What is the intensity level at…

a) 200 m b) .25 m c) 500 m

3) What is the speed of sound in air at…

a) 10 oC b) 50 oC c) 35 oC

4) A train approaching a station at a speed of 34 m/s sounds a 2000 Hz whistle. a) What is the apparent frequency heard by an observer standing at the station? b) What is the change in frequency heard as the train passes by?

5) A train going 40 m/s approaches a crossing bell whose frequency is 820 Hz. a) What frequency is heard by passengers on the approaching train? b) What frequency is heard by passengers after the train passes the bell?

6) A car traveling 30 m/s overtakes another car going only 25 m/s. When the faster car is behind the slower one, it sounds a horn of frequency 1500 Hz. What is the frequency heard by the driver of the slower car?

7) If you move at 18 m/s toward a 2300 Hz source that is moving toward you with a ground speed of 30 m/s, what frequency do you hear?

8) You standing by the railroad track when a train sounding a 750 Hz whistle passes you at 80 km/hr. What is the difference in the frequencies you hear as the train approaches and departs?

9) If two firecrackers produce a sound level of 95 dB when fired simultaneously at a certain place, what will be the sound level if only one exploded?

10) A person standing a certain distance from an airplane with four equally noisy jet engines is experiencing a sound level bordering on pain, 120 dB. What sound level would this person experience if the captain shut down all but one engine?

11) At a rock concert, a dB meter registered 130 dB when placed 2.8 m in front of a loudspeaker on the stage. a) What was the power output of the speaker, assuming uniform spherical spreading of sound and neglecting absorption in the air? b) How far away would you have to move for the sound to be 90 dB?