What is the intensity level in deibels of a sound that has an intensity of 3.1E-

Question

What is the intensity level in deibels of a sound that has an intensity of 3.1E-4 W/m2? Decibels = [Num]dB

What is the intensity of 70 dB sound? Intensity = [Num]W/m2

What is the speed of sound in air (M = 29 g/mol and gamma = 1.4) on a day when the tempearture is 33 degrees? Sound Speed = [Num]m/s

A sonar pulse is sent from one submarine to another submarine, where it is reflected and returned. If the round trip takes 6 seconds, how far away is the other submarine? (Assume the bulk modulus for seawater is 2.1 x 109 Pa and its density is 1030 kg/m3) Distance = [Num] [Units]

Young's modulus for steel is 2.07 x 1011 and it's density is 7,800 kg/m3. Compute the speed of sound in a steel rod. Sound Speed = [Num]m/s

What is the intensity of 70 dB sound? Intensity = [Num]W/m2

Explanation / Answer

intensity = 10*log(I/Io) = 10*log(3.1e-4/1e-12) = 84.9 decibels = 85(nearly)

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70 = 10*log*I/Io)

I = 10^7*Io = 10^7*10^-12 = 10^-5 W/m^2

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v = sqrt(gamma*R*T/M)

v = sqrt((1.4*8.314*306)/0.029) = 350.45 m/s

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speed v = sqrt(B/d) = sqrt(2.1e9/1030) = 1427.87 m/s

t = 2d/v

d = (v*t/2 = (1427.87*6)/2 = 4283.61 m

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v = sqrt(Y/d) = sqrt(2.07e11/7800) = 5151.55 m/s

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