In the upper atmosphere at altitudes where commercial airlines travel, we find extremely cold temperatures. What is the speed of sound (in metric units) for a temperature of 49.0 oC?
a. 984.9 m/s b. 300.8 m/s
c. 344.7 m/s d. 140.7 m/s
[Ques. 2] Harmonics
a. are components of a complex waveform.
b. have frequencies that are integer multiples of the frequency of the complex waveform.
c. are pure tones.
d. have sinusoidal waveforms.
e. all of the above
[Ques. 3] A sound with ten times the amplitude of another sound is judged to be
a. twice as loud. b. ten times as loud.
c. 10 dB higher in sound level. d. 20 dB higher in sound level.
[Ques. 4] If you move twice as far away from a lawn mower running in an open field, the amplitude of the sound you hear will be ___________ what it was before.
a. the same as
b. twice
c. half
d. four times
e. one fourth
[Ques. 5] If one lawn mower causes an 80-dB sound level at a point nearby, four lawnmowers together would cause a sound level of ____________ at that point.
a. 92 dB b. 84 dB
c. 86 dB d. none of the above
[Ques. 6] Combining two sounds of equal intensity will give a sound level ___________ than the sound level due to just one of them.
a. twice as loud b. 3 dB higher
c. 10 dB higher d. 2 dB higher
[Ques. 7] A zero decibel sound level
a. has zero amplitude. b. is nonsense.
c. is just at the threshold of hearing. d. none of the above
[Ques. 8] A sound level of 80 dB has ___________ the amplitude of a 60 dB sound.
a. ten times b. twenty times
c. one tenth d. twice
[Ques. 9] The 3rd harmonic of a complex tone has a frequency of 1,200 Hz. The frequency of the tone is
a. 200 Hz. b. 400 Hz.
c. 600 Hz. d. none of the above.
[Ques. 10] An echo is a sound wave that has been
a. diffracted.
b. refracted.
c. reflected.
d. reverberated.
e. amplified.
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