The intensity level in a truck is 93.0 dB. What is the intensity of this sound? ___mW/m2
A pair of in-phase stereo speakers is placed side by side, 0.58 m apart. You stand directly in front of one of the speakers, 1.0 m from the speaker. What is the lowest frequency that will produce constructive interference at your location? __kHz
thanks so much if you can help!
A pair of in-phase stereo speakers is placed side by side, 0.58 m apart. You stand directly in front of one of the speakers, 1.0 m from the speaker. What is the lowest frequency that will produce constructive interference at your location? __kHz
thanks so much if you can help!
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Hi. First, apologies for not completing a previous question properly; here's the missing part:
b) mu = 0.035kg/9.5m = 3.68 x10^-3 kg/m
For 8.0N: v = sqrt (8.0/(3.68 x10^-3)) = 46.63 m/s
For 9.0N: v = sqrt (9.0/(3.68 x10^-3)) = 49.45 m/s
I forgot the question wanted the times (not the speeds):
8.0N. Time = distance/speed = 9.5 / 46.63 = 0.204s
9.0N. Time = distance/speed = 9.5 / 49.45 = 0.192s
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Someone has laready answered part 2 of the current question, so I'll do part 1:
Intensity in dB = 10log(I/I_0) where I_0 is the threshold of hearing (=10^-12 W/m^2)
93.0 = 10log(I / 10^-12)
log(I / 10^-12) = 9.30
I/10^-12 = 10^9.30
I = 10^-12 x 10^9.30 = 2.00x10^-3 W/m^2
= 2.00mW/m^2
b) mu = 0.035kg/9.5m = 3.68 x10^-3 kg/m
For 8.0N: v = sqrt (8.0/(3.68 x10^-3)) = 46.63 m/s
For 9.0N: v = sqrt (9.0/(3.68 x10^-3)) = 49.45 m/s
I forgot the question wanted the times (not the speeds):
8.0N. Time = distance/speed = 9.5 / 46.63 = 0.204s
9.0N. Time = distance/speed = 9.5 / 49.45 = 0.192s
______________________________________…
Someone has laready answered part 2 of the current question, so I'll do part 1:
Intensity in dB = 10log(I/I_0) where I_0 is the threshold of hearing (=10^-12 W/m^2)
93.0 = 10log(I / 10^-12)
log(I / 10^-12) = 9.30
I/10^-12 = 10^9.30
I = 10^-12 x 10^9.30 = 2.00x10^-3 W/m^2
= 2.00mW/m^2
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I'll do the second.
Distance to further speaker = sqrt. (1^2 + .58^2), = 1.156m. It is 1m. to the nearest one.
Difference = 0.156m. For constructive interference, this must be a wavelength, or multiple whole wavelengths. For lowest frequency, you need the longest wavelength, so here you use a wavelength of 0.156m.
Using 343m/sec as speed of sound: Frequency = velocity/wavelength, = 343/0.156, = 2,198.7Hz., or 2.1987kHz.
If you commonly use another speed for sound, rework the mathematics.
Distance to further speaker = sqrt. (1^2 + .58^2), = 1.156m. It is 1m. to the nearest one.
Difference = 0.156m. For constructive interference, this must be a wavelength, or multiple whole wavelengths. For lowest frequency, you need the longest wavelength, so here you use a wavelength of 0.156m.
Using 343m/sec as speed of sound: Frequency = velocity/wavelength, = 343/0.156, = 2,198.7Hz., or 2.1987kHz.
If you commonly use another speed for sound, rework the mathematics.